diff --git a/doc/combiner-explainer.md b/doc/core/combiner-explainer.md
similarity index 100%
rename from doc/combiner-explainer.md
rename to doc/core/combiner-explainer.md
diff --git a/doc/epoll-polling-engine.md b/doc/core/epoll-polling-engine.md
similarity index 100%
rename from doc/epoll-polling-engine.md
rename to doc/core/epoll-polling-engine.md
diff --git a/doc/images/new_epoll_impl.png b/doc/core/images/new_epoll_impl.png
similarity index 100%
rename from doc/images/new_epoll_impl.png
rename to doc/core/images/new_epoll_impl.png
diff --git a/doc/images/old_epoll_impl.png b/doc/core/images/old_epoll_impl.png
similarity index 100%
rename from doc/images/old_epoll_impl.png
rename to doc/core/images/old_epoll_impl.png
diff --git a/tools/doxygen/Doxyfile.c++ b/tools/doxygen/Doxyfile.c++
index 40abd726c45..1abf6bddce1 100644
--- a/tools/doxygen/Doxyfile.c++
+++ b/tools/doxygen/Doxyfile.c++
@@ -764,7 +764,6 @@ INPUT                  = doc/PROTOCOL-HTTP2.md \
 doc/PROTOCOL-WEB.md \
 doc/binary-logging.md \
 doc/c-style-guide.md \
-doc/combiner-explainer.md \
 doc/command_line_tool.md \
 doc/compression.md \
 doc/compression_cookbook.md \
@@ -775,7 +774,6 @@ doc/cpp-style-guide.md \
 doc/cpp/pending_api_cleanups.md \
 doc/cpp/perf_notes.md \
 doc/environment_variables.md \
-doc/epoll-polling-engine.md \
 doc/fail_fast.md \
 doc/fork_support.md \
 doc/g_stands_for.md \
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 8fed2721594..790d756680d 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -764,7 +764,6 @@ INPUT                  = doc/PROTOCOL-HTTP2.md \
 doc/PROTOCOL-WEB.md \
 doc/binary-logging.md \
 doc/c-style-guide.md \
-doc/combiner-explainer.md \
 doc/command_line_tool.md \
 doc/compression.md \
 doc/compression_cookbook.md \
@@ -775,7 +774,6 @@ doc/cpp-style-guide.md \
 doc/cpp/pending_api_cleanups.md \
 doc/cpp/perf_notes.md \
 doc/environment_variables.md \
-doc/epoll-polling-engine.md \
 doc/fail_fast.md \
 doc/fork_support.md \
 doc/g_stands_for.md \
diff --git a/tools/doxygen/Doxyfile.core b/tools/doxygen/Doxyfile.core
index 973975ae283..b78fb607ad3 100644
--- a/tools/doxygen/Doxyfile.core
+++ b/tools/doxygen/Doxyfile.core
@@ -764,13 +764,14 @@ INPUT                  = doc/PROTOCOL-HTTP2.md \
 doc/PROTOCOL-WEB.md \
 doc/binary-logging.md \
 doc/c-style-guide.md \
-doc/combiner-explainer.md \
 doc/command_line_tool.md \
 doc/compression.md \
 doc/compression_cookbook.md \
 doc/connection-backoff-interop-test-description.md \
 doc/connection-backoff.md \
 doc/connectivity-semantics-and-api.md \
+doc/core/combiner-explainer.md \
+doc/core/epoll-polling-engine.md \
 doc/core/grpc-client-server-polling-engine-usage.md \
 doc/core/grpc-cq.md \
 doc/core/grpc-error.md \
@@ -780,7 +781,6 @@ doc/core/pending_api_cleanups.md \
 doc/core/transport_explainer.md \
 doc/cpp-style-guide.md \
 doc/environment_variables.md \
-doc/epoll-polling-engine.md \
 doc/fail_fast.md \
 doc/fork_support.md \
 doc/g_stands_for.md \
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 204ef493bac..f0007145e37 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -764,13 +764,14 @@ INPUT                  = doc/PROTOCOL-HTTP2.md \
 doc/PROTOCOL-WEB.md \
 doc/binary-logging.md \
 doc/c-style-guide.md \
-doc/combiner-explainer.md \
 doc/command_line_tool.md \
 doc/compression.md \
 doc/compression_cookbook.md \
 doc/connection-backoff-interop-test-description.md \
 doc/connection-backoff.md \
 doc/connectivity-semantics-and-api.md \
+doc/core/combiner-explainer.md \
+doc/core/epoll-polling-engine.md \
 doc/core/grpc-client-server-polling-engine-usage.md \
 doc/core/grpc-cq.md \
 doc/core/grpc-error.md \
@@ -780,7 +781,6 @@ doc/core/pending_api_cleanups.md \
 doc/core/transport_explainer.md \
 doc/cpp-style-guide.md \
 doc/environment_variables.md \
-doc/epoll-polling-engine.md \
 doc/fail_fast.md \
 doc/fork_support.md \
 doc/g_stands_for.md \