diff --git a/tree/ntuple/inc/ROOT/REntry.hxx b/tree/ntuple/inc/ROOT/REntry.hxx
index 590e39853eff2..b97ecadd8a3f7 100644
--- a/tree/ntuple/inc/ROOT/REntry.hxx
+++ b/tree/ntuple/inc/ROOT/REntry.hxx
@@ -32,14 +32,11 @@ namespace ROOT {
 
 class RNTupleFillContext;
 class RNTupleReader;
-
-namespace Experimental {
 class RNTupleAttrSetReader;
 
 namespace Internal {
 struct RNTupleAttrEntry;
 }
-} // namespace Experimental
 
 // clang-format off
 /**
@@ -55,8 +52,8 @@ class REntry {
    friend class RNTupleFillContext;
    friend class RNTupleModel;
    friend class RNTupleReader;
-   friend class Experimental::RNTupleAttrSetReader;
-   friend struct Experimental::Internal::RNTupleAttrEntry;
+   friend class RNTupleAttrSetReader;
+   friend struct Internal::RNTupleAttrEntry;
 
 private:
    /// The entry must be linked to a specific model, identified by a model ID
diff --git a/tree/ntuple/inc/ROOT/RFieldBase.hxx b/tree/ntuple/inc/ROOT/RFieldBase.hxx
index 70880e3e3cfda..ac6e9891cd679 100644
--- a/tree/ntuple/inc/ROOT/RFieldBase.hxx
+++ b/tree/ntuple/inc/ROOT/RFieldBase.hxx
@@ -45,9 +45,7 @@ class RFieldVisitor;
 class RRawPtrWriteEntry;
 } // namespace Detail
 
-namespace Experimental {
 class RNTupleAttrSetReader;
-}
 
 namespace Internal {
 
@@ -65,11 +63,8 @@ ROOT::RResult<std::unique_ptr<ROOT::RFieldBase>>
 CallFieldBaseCreate(const std::string &fieldName, const std::string &typeName, const ROOT::RCreateFieldOptions &options,
                     const ROOT::RNTupleDescriptor *desc, ROOT::DescriptorId_t fieldId);
 
-} // namespace Internal
-
-namespace Experimental::Internal {
 struct RNTupleAttrEntry;
-}
+} // namespace Internal
 
 // clang-format off
 /**
@@ -89,7 +84,7 @@ This is and can only be partially enforced through C++.
 class RFieldBase {
    friend class RFieldZero;                                    // to reset fParent pointer in ReleaseSubfields()
    friend class ROOT::Detail::RRawPtrWriteEntry;               // to call Append()
-   friend class ROOT::Experimental::RNTupleAttrSetReader;      // for field->Read() in LoadEntry()
+   friend class ROOT::RNTupleAttrSetReader;      // for field->Read() in LoadEntry()
    friend struct ROOT::Internal::RFieldCallbackInjector;       // used for unit tests
    friend struct ROOT::Internal::RFieldRepresentationModifier; // used for unit tests
    friend void Internal::CallFlushColumnsOnField(RFieldBase &);
@@ -771,7 +766,7 @@ public:
 class RFieldBase::RValue final {
    friend class RFieldBase;
    friend class ROOT::REntry;
-   friend struct ROOT::Experimental::Internal::RNTupleAttrEntry;
+   friend struct ROOT::Internal::RNTupleAttrEntry;
 
 private:
    RFieldBase *fField = nullptr;  ///< The field that created the RValue
diff --git a/tree/ntuple/inc/ROOT/RNTupleAttrReading.hxx b/tree/ntuple/inc/ROOT/RNTupleAttrReading.hxx
index e75e4cbbbc88a..5428101e0b491 100644
--- a/tree/ntuple/inc/ROOT/RNTupleAttrReading.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleAttrReading.hxx
@@ -22,13 +22,11 @@ class REntry;
 class RNTupleDescriptor;
 class RNTupleModel;
 
-namespace Experimental {
-
 class RNTupleAttrEntryIterable;
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrRange
+\class ROOT::RNTupleAttrRange
 \ingroup NTuple
 \brief A range of main entries referred to by an attribute entry
 
@@ -83,7 +81,7 @@ public:
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrSetReader
+\class ROOT::RNTupleAttrSetReader
 \ingroup NTuple
 \brief Class used to read a RNTupleAttrSet in the context of a RNTupleReader
 
@@ -163,7 +161,7 @@ public:
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrEntryIterable
+\class ROOT::RNTupleAttrEntryIterable
 \ingroup NTuple
 \brief Iterable class used to loop over attribute entries.
 
@@ -237,7 +235,6 @@ public:
    RIterator end() { return RIterator{fReader->fEntryRanges.end(), fReader->fEntryRanges.end(), fFilter}; }
 };
 
-} // namespace Experimental
 } // namespace ROOT
 
 #endif
diff --git a/tree/ntuple/inc/ROOT/RNTupleAttrUtils.hxx b/tree/ntuple/inc/ROOT/RNTupleAttrUtils.hxx
index bf24e3db6d481..7c84ea0acf315 100644
--- a/tree/ntuple/inc/ROOT/RNTupleAttrUtils.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleAttrUtils.hxx
@@ -10,7 +10,7 @@
 #include <cstddef>
 #include <cstdint>
 
-namespace ROOT::Experimental::Internal::RNTupleAttributes {
+namespace ROOT::Internal::RNTupleAttributes {
 
 /*
 Attribute RNTuples have a fixed Model schema that looks like this:
@@ -48,6 +48,6 @@ enum : std::size_t {
 inline constexpr const char *kMetaFieldNames[] = {"_rangeStart", "_rangeLen", "_userData"};
 static_assert(kMetaFieldIndex_Count == sizeof(kMetaFieldNames) / sizeof(kMetaFieldNames[0]));
 
-} // namespace ROOT::Experimental::Internal::RNTupleAttributes
+} // namespace ROOT::Internal::RNTupleAttributes
 
 #endif
diff --git a/tree/ntuple/inc/ROOT/RNTupleAttrWriting.hxx b/tree/ntuple/inc/ROOT/RNTupleAttrWriting.hxx
index bc5861fd990e1..af94664e34e69 100644
--- a/tree/ntuple/inc/ROOT/RNTupleAttrWriting.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleAttrWriting.hxx
@@ -20,15 +20,13 @@ class RNTupleModel;
 class RNTuple;
 class RNTupleWriter;
 
-namespace Experimental {
-
 class RNTupleAttrSetWriter;
 
 namespace Internal {
 
 // clang-format off
 /**
-\class ROOT::Experimental::Internal::RNTupleAttrEntry
+\class ROOT::Internal::RNTupleAttrEntry
 \ingroup NTuple
 \brief A pair of scoped + meta entry used by the RNTupleAttrSetWriter.
 
@@ -49,7 +47,7 @@ struct RNTupleAttrEntry {
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrPendingRange
+\class ROOT::RNTupleAttrPendingRange
 \ingroup NTuple
 \brief A not-yet-finalized Attribute Range used for writing
 
@@ -59,7 +57,7 @@ For the same reason, it can only be created by the AttrSetWriter.
 */
 // clang-format on
 class RNTupleAttrPendingRange final {
-   friend class ROOT::Experimental::RNTupleAttrSetWriter;
+   friend class ROOT::RNTupleAttrSetWriter;
 
    ROOT::NTupleSize_t fStart = 0;
    std::uint64_t fModelId = 0;
@@ -113,7 +111,7 @@ public:
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrSetWriter
+\class ROOT::RNTupleAttrSetWriter
 \ingroup NTuple
 \brief Class used to write an RNTupleAttrSet in the context of an RNTupleWriter.
 
@@ -205,7 +203,7 @@ public:
 
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrSetWriterHandle
+\class ROOT::RNTupleAttrSetWriterHandle
 \ingroup NTuple
 \brief Non-owning handle to an RNTupleAttrSetWriter
 
@@ -238,7 +236,6 @@ public:
    }
 };
 
-} // namespace Experimental
 } // namespace ROOT
 
 #endif
diff --git a/tree/ntuple/inc/ROOT/RNTupleDescriptor.hxx b/tree/ntuple/inc/ROOT/RNTupleDescriptor.hxx
index ced1b64c15aba..b7a07fcab174b 100644
--- a/tree/ntuple/inc/ROOT/RNTupleDescriptor.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleDescriptor.hxx
@@ -58,6 +58,7 @@ class RClusterGroupDescriptorBuilder;
 class RExtraTypeInfoDescriptorBuilder;
 class RFieldDescriptorBuilder;
 class RNTupleDescriptorBuilder;
+class RNTupleAttrSetDescriptorBuilder;
 
 RNTupleDescriptor CloneDescriptorSchema(const RNTupleDescriptor &desc);
 struct RNTupleClusterBoundaries {
@@ -68,18 +69,16 @@ struct RNTupleClusterBoundaries {
 std::vector<ROOT::Internal::RNTupleClusterBoundaries> GetClusterBoundaries(const RNTupleDescriptor &desc);
 } // namespace Internal
 
-namespace Experimental {
-
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrSetDescriptor
+\class ROOT::RNTupleAttrSetDescriptor
 \ingroup NTuple
 \brief Metadata stored for every Attribute Set linked to an RNTuple.
 */
 // clang-format on
 class RNTupleAttrSetDescriptor final {
-   friend class Experimental::Internal::RNTupleAttrSetDescriptorBuilder;
-
+   friend class Internal::RNTupleAttrSetDescriptorBuilder;
+   
    std::uint16_t fSchemaVersionMajor = 0;
    std::uint16_t fSchemaVersionMinor = 0;
    std::uint32_t fAnchorLength = 0; ///< uncompressed size of the linked anchor
@@ -108,10 +107,6 @@ public:
    RNTupleAttrSetDescriptor Clone() const;
 };
 
-class RNTupleAttrSetDescriptorIterable;
-
-} // namespace Experimental
-
 // clang-format off
 /**
 \class ROOT::RFieldDescriptor
@@ -765,7 +760,7 @@ private:
    /// Potentially a subset of all the available clusters
    std::unordered_map<ROOT::DescriptorId_t, RClusterDescriptor> fClusterDescriptors;
    /// List of AttributeSets linked to this RNTuple
-   std::vector<Experimental::RNTupleAttrSetDescriptor> fAttributeSets;
+   std::vector<RNTupleAttrSetDescriptor> fAttributeSets;
 
    // We don't expose this publicly because when we add sharded clusters, this interface does not make sense anymore
    ROOT::DescriptorId_t FindClusterId(ROOT::NTupleSize_t entryIdx) const;
@@ -806,7 +801,7 @@ public:
    class RClusterGroupDescriptorIterable;
    class RClusterDescriptorIterable;
    class RExtraTypeInfoDescriptorIterable;
-   friend class Experimental::RNTupleAttrSetDescriptorIterable;
+   class RNTupleAttrSetDescriptorIterable;
 
    /// Modifiers passed to CreateModel()
    struct RCreateModelOptions {
@@ -907,7 +902,7 @@ public:
 
    RExtraTypeInfoDescriptorIterable GetExtraTypeInfoIterable() const;
 
-   ROOT::Experimental::RNTupleAttrSetDescriptorIterable GetAttrSetIterable() const;
+   RNTupleAttrSetDescriptorIterable GetAttrSetIterable() const;
 
    const std::string &GetName() const { return fName; }
    const std::string &GetDescription() const { return fDescription; }
@@ -1316,16 +1311,15 @@ public:
    RIterator end() { return RIterator(fNTuple.fExtraTypeInfoDescriptors.cend()); }
 };
 
-namespace Experimental {
 // clang-format off
 /**
-\class ROOT::Experimental::RNTupleAttrSetDescriptorIterable
+\class ROOT::RNTupleAttrSetDescriptorIterable
 \ingroup NTuple
 \brief Used to loop over all the Attribute Sets linked to an RNTuple
 */
 // clang-format on
 // TODO: move this to RNTupleDescriptor::RNTupleAttrSetDescriptorIterable when it moves out of Experimental.
-class RNTupleAttrSetDescriptorIterable final {
+class RNTupleDescriptor::RNTupleAttrSetDescriptorIterable final {
 private:
    /// The associated RNTuple for this range.
    const RNTupleDescriptor &fNTuple;
@@ -1368,7 +1362,6 @@ public:
    RIterator begin() { return RIterator(fNTuple.fAttributeSets.cbegin()); }
    RIterator end() { return RIterator(fNTuple.fAttributeSets.cend()); }
 };
-} // namespace Experimental
 
 // clang-format off
 /**
@@ -1444,9 +1437,9 @@ public:
    }
 };
 
-namespace Experimental::Internal {
+namespace Internal {
 class RNTupleAttrSetDescriptorBuilder final {
-   ROOT::Experimental::RNTupleAttrSetDescriptor fDesc;
+   ROOT::RNTupleAttrSetDescriptor fDesc;
 
 public:
    RNTupleAttrSetDescriptorBuilder &Name(std::string_view name)
@@ -1473,11 +1466,8 @@ public:
 
    /// Attempt to make an AttributeSet descriptor. This may fail if the builder
    /// was not given enough information to make a proper descriptor.
-   RResult<ROOT::Experimental::RNTupleAttrSetDescriptor> MoveDescriptor();
+   RResult<ROOT::RNTupleAttrSetDescriptor> MoveDescriptor();
 };
-} // namespace Experimental::Internal
-
-namespace Internal {
 
 // clang-format off
 /**
@@ -1884,7 +1874,7 @@ public:
    RResult<void> AddExtraTypeInfo(RExtraTypeInfoDescriptor &&extraTypeInfoDesc);
    void ReplaceExtraTypeInfo(RExtraTypeInfoDescriptor &&extraTypeInfoDesc);
 
-   RResult<void> AddAttributeSet(Experimental::RNTupleAttrSetDescriptor &&attrSetDesc);
+   RResult<void> AddAttributeSet(RNTupleAttrSetDescriptor &&attrSetDesc);
 
    /// Mark the beginning of the header extension; any fields and columns added after a call to this function are
    /// annotated as begin part of the header extension.
diff --git a/tree/ntuple/inc/ROOT/RNTupleFillContext.hxx b/tree/ntuple/inc/ROOT/RNTupleFillContext.hxx
index 45ffdd61a7ca8..fed28727a6555 100644
--- a/tree/ntuple/inc/ROOT/RNTupleFillContext.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleFillContext.hxx
@@ -30,9 +30,7 @@
 
 namespace ROOT {
 
-namespace Experimental {
 class RNTupleAttrSetWriter;
-}
 
 // clang-format off
 /**
@@ -52,7 +50,7 @@ sequential writing, please refer to RNTupleWriter.
 class RNTupleFillContext {
    friend class ROOT::RNTupleWriter;
    friend class RNTupleParallelWriter;
-   friend class ROOT::Experimental::RNTupleAttrSetWriter;
+   friend class ROOT::RNTupleAttrSetWriter;
 
 private:
    /// The page sink's parallel page compression scheduler if IMT is on.
diff --git a/tree/ntuple/inc/ROOT/RNTupleReader.hxx b/tree/ntuple/inc/ROOT/RNTupleReader.hxx
index c93d558c89b81..26c61130c7e1c 100644
--- a/tree/ntuple/inc/ROOT/RNTupleReader.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleReader.hxx
@@ -530,7 +530,7 @@ public:
    /// Looks for an attribute set with the given name and creates an RNTupleAttrSetReader for it, with the provided
    /// read options.
    /// The returned reader has an independent lifetime from this RNTupleReader.
-   std::unique_ptr<Experimental::RNTupleAttrSetReader>
+   std::unique_ptr<RNTupleAttrSetReader>
    OpenAttributeSet(std::string_view attrSetName, const ROOT::RNTupleReadOptions &options = {});
 }; // class RNTupleReader
 
diff --git a/tree/ntuple/inc/ROOT/RNTupleSerialize.hxx b/tree/ntuple/inc/ROOT/RNTupleSerialize.hxx
index 0f80b0e8c170d..ee91fe9483c3e 100644
--- a/tree/ntuple/inc/ROOT/RNTupleSerialize.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleSerialize.hxx
@@ -34,16 +34,11 @@ namespace ROOT {
 class RNTupleDescriptor;
 class RClusterDescriptor;
 enum class EExtraTypeInfoIds;
-
-namespace Experimental {
 class RNTupleAttrSetDescriptor;
-namespace Internal {
-class RNTupleAttrSetDescriptorBuilder;
-} // namespace Internal
-} // namespace Experimental
 
 namespace Internal {
 
+class RNTupleAttrSetDescriptorBuilder;
 class RClusterDescriptorBuilder;
 class RNTupleDescriptorBuilder;
 
@@ -279,10 +274,10 @@ public:
                                                               ROOT::Internal::RNTupleDescriptorBuilder &descBuilder);
 
    static RResult<std::uint32_t>
-   SerializeAttributeSet(const Experimental::RNTupleAttrSetDescriptor &attrSetDesc, void *buffer);
+   SerializeAttributeSet(const RNTupleAttrSetDescriptor &attrSetDesc, void *buffer);
    static RResult<std::uint32_t>
    DeserializeAttributeSet(const void *buffer, std::uint64_t bufSize,
-                           Experimental::Internal::RNTupleAttrSetDescriptorBuilder &attrSetDescBld);
+                           Internal::RNTupleAttrSetDescriptorBuilder &attrSetDescBld);
 
    static RResult<RContext> SerializeHeader(void *buffer, const RNTupleDescriptor &desc);
    static RResult<std::uint32_t> SerializePageList(void *buffer, const RNTupleDescriptor &desc,
diff --git a/tree/ntuple/inc/ROOT/RNTupleWriter.hxx b/tree/ntuple/inc/ROOT/RNTupleWriter.hxx
index fef31b7304684..40fae7155b61d 100644
--- a/tree/ntuple/inc/ROOT/RNTupleWriter.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleWriter.hxx
@@ -35,9 +35,9 @@ class TDirectory;
 namespace ROOT {
 
 class RNTupleWriteOptions;
+class RNTupleAttrSetWriterHandle;
 
 namespace Experimental {
-class RNTupleAttrSetWriterHandle;
 class RFile;
 
 /// Creates an RNTupleWriter that writes into the given `file`, appending to it. The RNTuple is written under the
@@ -126,7 +126,7 @@ private:
    RNTupleFillContext fFillContext;
    Experimental::Detail::RNTupleMetrics fMetrics;
    /// All the Attribute Sets created from this Writer.
-   std::vector<std::shared_ptr<Experimental::RNTupleAttrSetWriter>> fAttributeSets;
+   std::vector<std::shared_ptr<RNTupleAttrSetWriter>> fAttributeSets;
 
    ROOT::NTupleSize_t fLastCommittedClusterGroup = 0;
 
@@ -138,7 +138,7 @@ private:
    // Helper function that is called from CommitCluster() when necessary
    void CommitClusterGroup();
 
-   void CloseAttributeSetImpl(ROOT::Experimental::RNTupleAttrSetWriter &attrSet);
+   void CloseAttributeSetImpl(ROOT::RNTupleAttrSetWriter &attrSet);
 
    /// Create a writer, potentially wrapping the sink in a RPageSinkBuf.
    static std::unique_ptr<RNTupleWriter> Create(std::unique_ptr<ROOT::RNTupleModel> model,
@@ -271,14 +271,14 @@ public:
    /// the main writer.
    /// \warning Currently this is only supported for writers created via RNTupleWriter::Append(). This limitation
    /// will be lifted in the future.
-   ROOT::Experimental::RNTupleAttrSetWriterHandle
+   ROOT::RNTupleAttrSetWriterHandle
    CreateAttributeSet(std::unique_ptr<RNTupleModel> model, std::string_view name,
                       const ROOT::RNTupleWriteOptions *options = nullptr);
 
    /// Writes the given AttributeSet to the underlying storage and closes it. This method is only useful if you
    /// want to close the AttributeSet early: otherwise it will automatically closed when the RNTupleWriter gets
    /// destroyed.
-   void CloseAttributeSet(ROOT::Experimental::RNTupleAttrSetWriterHandle handle);
+   void CloseAttributeSet(ROOT::RNTupleAttrSetWriterHandle handle);
 }; // class RNTupleWriter
 
 } // namespace ROOT
diff --git a/tree/ntuple/src/RNTupleAttrReading.cxx b/tree/ntuple/src/RNTupleAttrReading.cxx
index 800586efa69e5..aa23fa1a3262d 100644
--- a/tree/ntuple/src/RNTupleAttrReading.cxx
+++ b/tree/ntuple/src/RNTupleAttrReading.cxx
@@ -14,10 +14,9 @@
 #include <cstddef>
 #include <utility>
 
-using namespace ROOT::Experimental::Internal::RNTupleAttributes;
+using namespace ROOT::Internal::RNTupleAttributes;
 
-ROOT::Experimental::RNTupleAttrSetReader::RNTupleAttrSetReader(std::unique_ptr<RNTupleReader> reader,
-                                                               std::uint16_t vSchemaMajor)
+ROOT::RNTupleAttrSetReader::RNTupleAttrSetReader(std::unique_ptr<RNTupleReader> reader, std::uint16_t vSchemaMajor)
    : fReader(std::move(reader))
 {
    // Changes in major version imply forward incompatibility
@@ -68,13 +67,12 @@ ROOT::Experimental::RNTupleAttrSetReader::RNTupleAttrSetReader(std::unique_ptr<R
    R__LOG_INFO(ROOT::Internal::NTupleLog()) << "Loaded " << fEntryRanges.size() << " attribute entries.";
 }
 
-const ROOT::RNTupleDescriptor &ROOT::Experimental::RNTupleAttrSetReader::GetDescriptor() const
+const ROOT::RNTupleDescriptor &ROOT::RNTupleAttrSetReader::GetDescriptor() const
 {
    return fReader->GetDescriptor();
 }
 
-ROOT::Experimental::RNTupleAttrRange
-ROOT::Experimental::RNTupleAttrSetReader::LoadEntry(ROOT::NTupleSize_t index, REntry &entry)
+ROOT::RNTupleAttrRange ROOT::RNTupleAttrSetReader::LoadEntry(ROOT::NTupleSize_t index, REntry &entry)
 {
    // TODO(gparolini): find a way to avoid this const_cast
    auto &metaModel = const_cast<ROOT::RNTupleModel &>(fReader->GetModel());
@@ -102,19 +100,19 @@ ROOT::Experimental::RNTupleAttrSetReader::LoadEntry(ROOT::NTupleSize_t index, RE
    return RNTupleAttrRange::FromStartLength(*pStart, *pLen);
 }
 
-ROOT::Experimental::RNTupleAttrRange ROOT::Experimental::RNTupleAttrSetReader::LoadEntry(ROOT::NTupleSize_t index)
+ROOT::RNTupleAttrRange ROOT::RNTupleAttrSetReader::LoadEntry(ROOT::NTupleSize_t index)
 {
    auto &entry = fUserModel->GetDefaultEntry();
    return LoadEntry(index, entry);
 }
 
-std::unique_ptr<ROOT::REntry> ROOT::Experimental::RNTupleAttrSetReader::CreateEntry()
+std::unique_ptr<ROOT::REntry> ROOT::RNTupleAttrSetReader::CreateEntry()
 {
    return fUserModel->CreateEntry();
 }
 
-ROOT::Experimental::RNTupleAttrEntryIterable
-ROOT::Experimental::RNTupleAttrSetReader::GetAttributesContainingRange(NTupleSize_t startEntry, NTupleSize_t endEntry)
+ROOT::RNTupleAttrEntryIterable
+ROOT::RNTupleAttrSetReader::GetAttributesContainingRange(NTupleSize_t startEntry, NTupleSize_t endEntry)
 {
    RNTupleAttrRange range;
    if (endEntry <= startEntry) {
@@ -130,8 +128,8 @@ ROOT::Experimental::RNTupleAttrSetReader::GetAttributesContainingRange(NTupleSiz
    return RNTupleAttrEntryIterable{*this, filter};
 }
 
-ROOT::Experimental::RNTupleAttrEntryIterable
-ROOT::Experimental::RNTupleAttrSetReader::GetAttributesInRange(NTupleSize_t startEntry, NTupleSize_t endEntry)
+ROOT::RNTupleAttrEntryIterable
+ROOT::RNTupleAttrSetReader::GetAttributesInRange(NTupleSize_t startEntry, NTupleSize_t endEntry)
 {
    RNTupleAttrRange range;
    if (endEntry <= startEntry) {
@@ -147,15 +145,14 @@ ROOT::Experimental::RNTupleAttrSetReader::GetAttributesInRange(NTupleSize_t star
    return RNTupleAttrEntryIterable{*this, filter};
 }
 
-ROOT::Experimental::RNTupleAttrEntryIterable
-ROOT::Experimental::RNTupleAttrSetReader::GetAttributes(NTupleSize_t entryIndex)
+ROOT::RNTupleAttrEntryIterable ROOT::RNTupleAttrSetReader::GetAttributes(NTupleSize_t entryIndex)
 {
    RNTupleAttrEntryIterable::RFilter filter{RNTupleAttrRange::FromStartEnd(entryIndex, entryIndex + 1),
                                             /*fIsContained=*/false};
    return RNTupleAttrEntryIterable{*this, filter};
 }
 
-ROOT::Experimental::RNTupleAttrEntryIterable ROOT::Experimental::RNTupleAttrSetReader::GetAttributes()
+ROOT::RNTupleAttrEntryIterable ROOT::RNTupleAttrSetReader::GetAttributes()
 {
    return RNTupleAttrEntryIterable{*this};
 }
@@ -163,7 +160,7 @@ ROOT::Experimental::RNTupleAttrEntryIterable ROOT::Experimental::RNTupleAttrSetR
 //
 //  RNTupleAttrEntryIterable
 //
-bool ROOT::Experimental::RNTupleAttrEntryIterable::RIterator::FullyContained(RNTupleAttrRange range) const
+bool ROOT::RNTupleAttrEntryIterable::RIterator::FullyContained(RNTupleAttrRange range) const
 {
    assert(fFilter);
    if (fFilter->fIsContained) {
@@ -173,8 +170,7 @@ bool ROOT::Experimental::RNTupleAttrEntryIterable::RIterator::FullyContained(RNT
    }
 }
 
-ROOT::Experimental::RNTupleAttrEntryIterable::RIterator::Iter_t
-ROOT::Experimental::RNTupleAttrEntryIterable::RIterator::SkipFiltered() const
+ROOT::RNTupleAttrEntryIterable::RIterator::Iter_t ROOT::RNTupleAttrEntryIterable::RIterator::SkipFiltered() const
 {
    // If we have no filter, every entry is valid.
    if (!fFilter)
diff --git a/tree/ntuple/src/RNTupleAttrWriting.cxx b/tree/ntuple/src/RNTupleAttrWriting.cxx
index 4a1711f66d13b..2abd4c5ae26dc 100644
--- a/tree/ntuple/src/RNTupleAttrWriting.cxx
+++ b/tree/ntuple/src/RNTupleAttrWriting.cxx
@@ -11,7 +11,7 @@
 #include <ROOT/RPageStorageFile.hxx>
 #include <ROOT/StringUtils.hxx>
 
-using namespace ROOT::Experimental::Internal::RNTupleAttributes;
+using namespace ROOT::Internal::RNTupleAttributes;
 
 static ROOT::RResult<void> ValidateAttributeModel(const ROOT::RNTupleModel &model)
 {
@@ -30,7 +30,7 @@ static ROOT::RResult<void> ValidateAttributeModel(const ROOT::RNTupleModel &mode
 //
 //  RNTupleAttrEntry
 //
-std::size_t ROOT::Experimental::Internal::RNTupleAttrEntry::Append()
+std::size_t ROOT::Internal::RNTupleAttrEntry::Append()
 {
    std::size_t bytesWritten = 0;
    // Write the meta entry values
@@ -53,10 +53,10 @@ std::size_t ROOT::Experimental::Internal::RNTupleAttrEntry::Append()
 //
 //  RNTupleAttrSetWriter
 //
-std::unique_ptr<ROOT::Experimental::RNTupleAttrSetWriter>
-ROOT::Experimental::RNTupleAttrSetWriter::Create(const RNTupleFillContext &mainFillContext,
-                                                 std::unique_ptr<ROOT::Internal::RPageSink> sink,
-                                                 std::unique_ptr<RNTupleModel> userModel)
+std::unique_ptr<ROOT::RNTupleAttrSetWriter>
+ROOT::RNTupleAttrSetWriter::Create(const RNTupleFillContext &mainFillContext,
+                                   std::unique_ptr<ROOT::Internal::RPageSink> sink,
+                                   std::unique_ptr<RNTupleModel> userModel)
 
 {
    ValidateAttributeModel(*userModel).ThrowOnError();
@@ -90,12 +90,12 @@ ROOT::Experimental::RNTupleAttrSetWriter::Create(const RNTupleFillContext &mainF
                                std::move(rangeStartPtr), std::move(rangeLenPtr)));
 }
 
-ROOT::Experimental::RNTupleAttrSetWriter::RNTupleAttrSetWriter(const RNTupleFillContext &mainFillContext,
-                                                               std::unique_ptr<ROOT::Internal::RPageSink> sink,
-                                                               std::unique_ptr<RNTupleModel> metaModel,
-                                                               std::unique_ptr<RNTupleModel> userModel,
-                                                               std::shared_ptr<ROOT::NTupleSize_t> rangeStartPtr,
-                                                               std::shared_ptr<ROOT::NTupleSize_t> rangeLenPtr)
+ROOT::RNTupleAttrSetWriter::RNTupleAttrSetWriter(const RNTupleFillContext &mainFillContext,
+                                                 std::unique_ptr<ROOT::Internal::RPageSink> sink,
+                                                 std::unique_ptr<RNTupleModel> metaModel,
+                                                 std::unique_ptr<RNTupleModel> userModel,
+                                                 std::shared_ptr<ROOT::NTupleSize_t> rangeStartPtr,
+                                                 std::shared_ptr<ROOT::NTupleSize_t> rangeLenPtr)
    : fFillContext(std::move(metaModel), std::move(sink)),
      fMainFillContext(&mainFillContext),
      fUserModel(std::move(userModel)),
@@ -104,14 +104,13 @@ ROOT::Experimental::RNTupleAttrSetWriter::RNTupleAttrSetWriter(const RNTupleFill
 {
 }
 
-ROOT::Experimental::RNTupleAttrPendingRange ROOT::Experimental::RNTupleAttrSetWriter::BeginRange()
+ROOT::RNTupleAttrPendingRange ROOT::RNTupleAttrSetWriter::BeginRange()
 {
    const auto start = fMainFillContext->GetNEntries();
    return RNTupleAttrPendingRange{start, fFillContext.GetModel().GetModelId()};
 }
 
-void ROOT::Experimental::RNTupleAttrSetWriter::CommitRange(ROOT::Experimental::RNTupleAttrPendingRange pendingRange,
-                                                           REntry &entry)
+void ROOT::RNTupleAttrSetWriter::CommitRange(ROOT::RNTupleAttrPendingRange pendingRange, REntry &entry)
 {
    // NOTE: this has to happen before potentially throwing the exception, otherwise the pending range will log its
    // "was not committed" warning in addition to it.
@@ -134,12 +133,12 @@ void ROOT::Experimental::RNTupleAttrSetWriter::CommitRange(ROOT::Experimental::R
    fFillContext.FillImpl(pair);
 }
 
-void ROOT::Experimental::RNTupleAttrSetWriter::CommitRange(ROOT::Experimental::RNTupleAttrPendingRange pendingRange)
+void ROOT::RNTupleAttrSetWriter::CommitRange(ROOT::RNTupleAttrPendingRange pendingRange)
 {
    CommitRange(std::move(pendingRange), fUserModel->GetDefaultEntry());
 }
 
-ROOT::Internal::RNTupleLink ROOT::Experimental::RNTupleAttrSetWriter::Commit()
+ROOT::Internal::RNTupleLink ROOT::RNTupleAttrSetWriter::Commit()
 {
    fFillContext.FlushCluster();
    if (fFillContext.GetNEntries() > 0)
diff --git a/tree/ntuple/src/RNTupleDescriptor.cxx b/tree/ntuple/src/RNTupleDescriptor.cxx
index 90b1136b0ed34..8a026af9cc591 100644
--- a/tree/ntuple/src/RNTupleDescriptor.cxx
+++ b/tree/ntuple/src/RNTupleDescriptor.cxx
@@ -1167,8 +1167,8 @@ void ROOT::Internal::RNTupleDescriptorBuilder::SetFeature(unsigned int flag)
    fDescriptor.fFeatureFlags.insert(flag);
 }
 
-ROOT::RResult<ROOT::Experimental::RNTupleAttrSetDescriptor>
-ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder::MoveDescriptor()
+ROOT::RResult<ROOT::RNTupleAttrSetDescriptor>
+ROOT::Internal::RNTupleAttrSetDescriptorBuilder::MoveDescriptor()
 {
    if (fDesc.fName.empty())
       return R__FAIL("attribute set name cannot be empty");
@@ -1466,7 +1466,7 @@ void ROOT::Internal::RNTupleDescriptorBuilder::ReplaceExtraTypeInfo(RExtraTypeIn
 }
 
 ROOT::RResult<void>
-ROOT::Internal::RNTupleDescriptorBuilder::AddAttributeSet(Experimental::RNTupleAttrSetDescriptor &&attrSetDesc)
+ROOT::Internal::RNTupleDescriptorBuilder::AddAttributeSet(RNTupleAttrSetDescriptor &&attrSetDesc)
 {
    auto &attrSets = fDescriptor.fAttributeSets;
    if (std::find_if(attrSets.begin(), attrSets.end(), [&name = attrSetDesc.GetName()](const auto &desc) {
@@ -1557,19 +1557,19 @@ ROOT::RNTupleDescriptor::RExtraTypeInfoDescriptorIterable ROOT::RNTupleDescripto
    return RExtraTypeInfoDescriptorIterable(*this);
 }
 
-ROOT::Experimental::RNTupleAttrSetDescriptorIterable ROOT::RNTupleDescriptor::GetAttrSetIterable() const
+ROOT::RNTupleDescriptor::RNTupleAttrSetDescriptorIterable ROOT::RNTupleDescriptor::GetAttrSetIterable() const
 {
-   return Experimental::RNTupleAttrSetDescriptorIterable(*this);
+   return RNTupleAttrSetDescriptorIterable(*this);
 }
 
-bool ROOT::Experimental::RNTupleAttrSetDescriptor::operator==(const RNTupleAttrSetDescriptor &other) const
+bool ROOT::RNTupleAttrSetDescriptor::operator==(const RNTupleAttrSetDescriptor &other) const
 {
    return fAnchorLength == other.fAnchorLength && fSchemaVersionMajor == other.fSchemaVersionMajor &&
           fSchemaVersionMinor == other.fSchemaVersionMinor && fAnchorLocator == other.fAnchorLocator &&
           fName == other.fName;
 };
 
-ROOT::Experimental::RNTupleAttrSetDescriptor ROOT::Experimental::RNTupleAttrSetDescriptor::Clone() const
+ROOT::RNTupleAttrSetDescriptor ROOT::RNTupleAttrSetDescriptor::Clone() const
 {
    RNTupleAttrSetDescriptor desc;
    desc.fAnchorLength = fAnchorLength;
diff --git a/tree/ntuple/src/RNTupleReader.cxx b/tree/ntuple/src/RNTupleReader.cxx
index 960f1e83a0478..f0cc167616f44 100644
--- a/tree/ntuple/src/RNTupleReader.cxx
+++ b/tree/ntuple/src/RNTupleReader.cxx
@@ -342,7 +342,7 @@ ROOT::DescriptorId_t ROOT::RNTupleReader::RetrieveFieldId(std::string_view field
    return fieldId;
 }
 
-std::unique_ptr<ROOT::Experimental::RNTupleAttrSetReader>
+std::unique_ptr<ROOT::RNTupleAttrSetReader>
 ROOT::RNTupleReader::OpenAttributeSet(std::string_view attrSetName, const ROOT::RNTupleReadOptions &readOpts)
 {
    auto attrSets = GetDescriptor().GetAttrSetIterable();
@@ -354,7 +354,7 @@ ROOT::RNTupleReader::OpenAttributeSet(std::string_view attrSetName, const ROOT::
    auto attrSource = fSource->OpenWithDifferentAnchor({it->GetAnchorLocator(), it->GetAnchorLength()}, readOpts);
    auto newReader = std::unique_ptr<RNTupleReader>(new RNTupleReader(std::move(attrSource), readOpts));
    R__ASSERT(newReader);
-   auto attrSetReader = std::unique_ptr<ROOT::Experimental::RNTupleAttrSetReader>(
-      new ROOT::Experimental::RNTupleAttrSetReader(std::move(newReader), it->GetSchemaVersionMajor()));
+   auto attrSetReader = std::unique_ptr<ROOT::RNTupleAttrSetReader>(
+      new ROOT::RNTupleAttrSetReader(std::move(newReader), it->GetSchemaVersionMajor()));
    return attrSetReader;
 }
diff --git a/tree/ntuple/src/RNTupleSerialize.cxx b/tree/ntuple/src/RNTupleSerialize.cxx
index 4cc25e4339341..93671d31e0774 100644
--- a/tree/ntuple/src/RNTupleSerialize.cxx
+++ b/tree/ntuple/src/RNTupleSerialize.cxx
@@ -1906,7 +1906,7 @@ ROOT::RResult<std::uint32_t> ROOT::Internal::RNTupleSerializer::SerializeFooter(
 }
 
 ROOT::RResult<std::uint32_t>
-ROOT::Internal::RNTupleSerializer::SerializeAttributeSet(const Experimental::RNTupleAttrSetDescriptor &attrDesc,
+ROOT::Internal::RNTupleSerializer::SerializeAttributeSet(const RNTupleAttrSetDescriptor &attrDesc,
                                                          void *buffer)
 {
    auto base = reinterpret_cast<unsigned char *>(buffer);
@@ -2093,7 +2093,7 @@ ROOT::RResult<void> ROOT::Internal::RNTupleSerializer::DeserializeFooter(const v
                                         "back in the future (but your main data is)";
       }
       for (std::uint32_t attrSetId = 0; attrSetId < nAttributeSets; ++attrSetId) {
-         Experimental::Internal::RNTupleAttrSetDescriptorBuilder attrSetDescBld;
+         Internal::RNTupleAttrSetDescriptorBuilder attrSetDescBld;
          if (auto res = DeserializeAttributeSet(bytes, fnBufSizeLeft(), attrSetDescBld)) {
             descBuilder.AddAttributeSet(attrSetDescBld.MoveDescriptor().Unwrap());
             bytes += res.Unwrap();
@@ -2108,7 +2108,7 @@ ROOT::RResult<void> ROOT::Internal::RNTupleSerializer::DeserializeFooter(const v
 }
 
 ROOT::RResult<std::uint32_t> ROOT::Internal::RNTupleSerializer::DeserializeAttributeSet(
-   const void *buffer, std::uint64_t bufSize, Experimental::Internal::RNTupleAttrSetDescriptorBuilder &attrSetDescBld)
+   const void *buffer, std::uint64_t bufSize, Internal::RNTupleAttrSetDescriptorBuilder &attrSetDescBld)
 {
    auto base = reinterpret_cast<const unsigned char *>(buffer);
    auto bytes = base;
diff --git a/tree/ntuple/src/RNTupleWriter.cxx b/tree/ntuple/src/RNTupleWriter.cxx
index 2c320794a6e69..f19b298edef97 100644
--- a/tree/ntuple/src/RNTupleWriter.cxx
+++ b/tree/ntuple/src/RNTupleWriter.cxx
@@ -172,7 +172,7 @@ ROOT::Experimental::RNTupleWriter_Append(std::unique_ptr<ROOT::RNTupleModel> mod
    return ROOT::RNTupleWriter::Create(std::move(model), std::move(sink), options);
 }
 
-ROOT::Experimental::RNTupleAttrSetWriterHandle
+ROOT::RNTupleAttrSetWriterHandle
 ROOT::RNTupleWriter::CreateAttributeSet(std::unique_ptr<ROOT::RNTupleModel> model, std::string_view name,
                                         const ROOT::RNTupleWriteOptions *optsPtr)
 {
@@ -188,7 +188,7 @@ ROOT::RNTupleWriter::CreateAttributeSet(std::unique_ptr<ROOT::RNTupleModel> mode
    auto attrSink = fFillContext.fSink->CloneAsHidden(name, opts);
 
    std::string nameStr{name};
-   auto attrSet = Experimental::RNTupleAttrSetWriter::Create(fFillContext, std::move(attrSink), std::move(model));
+   auto attrSet = RNTupleAttrSetWriter::Create(fFillContext, std::move(attrSink), std::move(model));
 
    // check for duplicates
    auto existingIt = std::find_if(fAttributeSets.begin(), fAttributeSets.end(),
@@ -198,16 +198,16 @@ ROOT::RNTupleWriter::CreateAttributeSet(std::unique_ptr<ROOT::RNTupleModel> mode
                                      "', but one already exists with that name"));
 
    auto &addedSet = fAttributeSets.emplace_back(std::move(attrSet));
-   return Experimental::RNTupleAttrSetWriterHandle{addedSet};
+   return RNTupleAttrSetWriterHandle{addedSet};
 }
 
-void ROOT::RNTupleWriter::CloseAttributeSetImpl(ROOT::Experimental::RNTupleAttrSetWriter &attrSet)
+void ROOT::RNTupleWriter::CloseAttributeSetImpl(ROOT::RNTupleAttrSetWriter &attrSet)
 {
    auto attrAnchorInfo = attrSet.Commit();
    fFillContext.fSink->CommitAttributeSet(attrSet.GetDescriptor().GetName(), attrAnchorInfo);
 }
 
-void ROOT::RNTupleWriter::CloseAttributeSet(ROOT::Experimental::RNTupleAttrSetWriterHandle handle)
+void ROOT::RNTupleWriter::CloseAttributeSet(ROOT::RNTupleAttrSetWriterHandle handle)
 {
    auto writer = handle.fWriter.lock();
    if (writer) {
diff --git a/tree/ntuple/src/RPageStorage.cxx b/tree/ntuple/src/RPageStorage.cxx
index 3b2967bf6b5f1..c37e900ca37ca 100644
--- a/tree/ntuple/src/RPageStorage.cxx
+++ b/tree/ntuple/src/RPageStorage.cxx
@@ -51,7 +51,7 @@ using ROOT::Internal::RColumnDescriptorBuilder;
 using ROOT::Internal::RColumnElementBase;
 using ROOT::Internal::RExtraTypeInfoDescriptorBuilder;
 
-using ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder;
+using ROOT::Internal::RNTupleAttrSetDescriptorBuilder;
 
 using ROOT::Internal::RCluster;
 using ROOT::Internal::ROnDiskPage;
@@ -1670,7 +1670,7 @@ void ROOT::Internal::RPagePersistentSink::CommitClusterGroup()
 void ROOT::Internal::RPagePersistentSink::CommitAttributeSet(std::string_view attrSetName,
                                                              const RNTupleLink &attrAnchorInfo)
 {
-   using namespace ROOT::Experimental::Internal::RNTupleAttributes;
+   using namespace ROOT::Internal::RNTupleAttributes;
 
    RNTupleAttrSetDescriptorBuilder attrSetDescBuilder;
    auto attrSetDesc = attrSetDescBuilder.SchemaVersion(kSchemaVersionMajor, kSchemaVersionMinor)
diff --git a/tree/ntuple/test/ntuple_attributes.cxx b/tree/ntuple/test/ntuple_attributes.cxx
index c8ae7496d31b9..619c0154100db 100644
--- a/tree/ntuple/test/ntuple_attributes.cxx
+++ b/tree/ntuple/test/ntuple_attributes.cxx
@@ -3,7 +3,7 @@
 #include <ROOT/RNTupleAttrReading.hxx>
 #include <TKey.h>
 
-static std::size_t Count(ROOT::Experimental::RNTupleAttrEntryIterable iterable)
+static std::size_t Count(ROOT::RNTupleAttrEntryIterable iterable)
 {
    std::size_t n = 0;
    for ([[maybe_unused]] auto _ : iterable)
@@ -894,7 +894,7 @@ TEST(RNTupleAttributes, InvalidPendingRange)
    auto attrModel = RNTupleModel::Create();
    auto attrSet = writer->CreateAttributeSet(std::move(attrModel), "MyAttributes");
 
-   ROOT::Experimental::RNTupleAttrPendingRange attrRange;
+   ROOT::RNTupleAttrPendingRange attrRange;
    EXPECT_FALSE(attrRange);
    try {
       attrSet->CommitRange(std::move(attrRange));
diff --git a/tree/ntuple/test/ntuple_descriptor.cxx b/tree/ntuple/test/ntuple_descriptor.cxx
index 8367608bae62a..88d8c5aefbd3f 100644
--- a/tree/ntuple/test/ntuple_descriptor.cxx
+++ b/tree/ntuple/test/ntuple_descriptor.cxx
@@ -422,7 +422,7 @@ TEST(RNTupleDescriptor, AttributeSets)
    RNTupleLocator locator;
    locator.SetType(ROOT::RNTupleLocator::kTypeFile);
    locator.SetPosition(128ul);
-   ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder builder;
+   ROOT::Internal::RNTupleAttrSetDescriptorBuilder builder;
    builder.SchemaVersion(1, 0).AnchorLength(1024).AnchorLocator(locator).Name("AttrSetName");
    RNTupleDescriptorBuilder descBuilder;
    descBuilder.SetVersion(1, 0, 1, 0);
diff --git a/tree/ntuple/test/ntuple_serialize.cxx b/tree/ntuple/test/ntuple_serialize.cxx
index cbe962540abce..01d5b3953d705 100644
--- a/tree/ntuple/test/ntuple_serialize.cxx
+++ b/tree/ntuple/test/ntuple_serialize.cxx
@@ -2207,7 +2207,7 @@ TEST(RNTuple, SerializeAttrSets)
    RNTupleLocator locator;
    locator.SetType(ROOT::RNTupleLocator::kTypeFile);
    locator.SetPosition(128ul);
-   ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder builder;
+   ROOT::Internal::RNTupleAttrSetDescriptorBuilder builder;
    builder.SchemaVersion(1, 0).AnchorLength(1024).AnchorLocator(locator).Name("AttrSetName");
    auto attrSetDesc = builder.MoveDescriptor().Unwrap();
 
@@ -2217,7 +2217,7 @@ TEST(RNTuple, SerializeAttrSets)
    res = RNTupleSerializer::SerializeAttributeSet(attrSetDesc, buf.get());
    ASSERT_TRUE(bool(buf));
 
-   ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder deserializedDescBld;
+   ROOT::Internal::RNTupleAttrSetDescriptorBuilder deserializedDescBld;
    RNTupleSerializer::DeserializeAttributeSet(buf.get(), res.Unwrap(), deserializedDescBld);
 
    ASSERT_EQ(attrSetDesc, deserializedDescBld.MoveDescriptor().Unwrap());
@@ -2269,7 +2269,7 @@ TEST(RNTuple, SerializeDescriptorWithAttrSets)
    locator.SetType(ROOT::RNTupleLocator::kTypeFile);
    locator.SetPosition(128ul);
 
-   ROOT::Experimental::Internal::RNTupleAttrSetDescriptorBuilder attrBuilder;
+   ROOT::Internal::RNTupleAttrSetDescriptorBuilder attrBuilder;
    attrBuilder.SchemaVersion(1, 0).AnchorLength(1024).AnchorLocator(locator).Name("AttrSetName");
 
    // First cluster