diff --git a/Mesh_3/include/CGAL/Polyhedral_mesh_domain_3.h b/Mesh_3/include/CGAL/Polyhedral_mesh_domain_3.h
index 7ed3dcfdfc9..1ba7188feeb 100644
--- a/Mesh_3/include/CGAL/Polyhedral_mesh_domain_3.h
+++ b/Mesh_3/include/CGAL/Polyhedral_mesh_domain_3.h
@@ -27,7 +27,7 @@
 #ifndef CGAL_POLYHEDRAL_MESH_DOMAIN_3_H
 #define CGAL_POLYHEDRAL_MESH_DOMAIN_3_H
 
-#include <CGAL/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h>
+#include <CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h>
 
 #include <CGAL/Mesh_3/Robust_intersection_traits_3.h>
 #include <CGAL/Mesh_3/Triangle_accessor_primitive.h>
diff --git a/Polygon_mesh_processing/include/CGAL/Point_inside_polygon_mesh.h b/Polygon_mesh_processing/include/CGAL/Point_inside_polygon_mesh.h
index acb7d9bc79f..904e0bd6d96 100644
--- a/Polygon_mesh_processing/include/CGAL/Point_inside_polygon_mesh.h
+++ b/Polygon_mesh_processing/include/CGAL/Point_inside_polygon_mesh.h
@@ -22,7 +22,7 @@
 #ifndef CGAL_POINT_INSIDE_POLYGON_MESH_H
 #define CGAL_POINT_INSIDE_POLYGON_MESH_H
 
-#include <CGAL/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h>
+#include <CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h>
 #include <CGAL/AABB_face_graph_triangle_primitive.h>
 
 #include <CGAL/AABB_tree.h>
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/fair.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/fair.h
index d857e65cd1e..7be4988b9a9 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/fair.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/fair.h
@@ -1,7 +1,7 @@
 #ifndef CGAL_POLYGON_MESH_PROCESSING_FAIR_H
 #define CGAL_POLYGON_MESH_PROCESSING_FAIR_H
 
-#include <CGAL/internal/Meshing_functions/Fair_Polyhedron_3.h>
+#include <CGAL/Polygon_mesh_processing/internal/Meshing_functions/Fair_Polyhedron_3.h>
 
 namespace CGAL {
 
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/TODO.txt b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/TODO.txt
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Hole_filling/TODO.txt
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/TODO.txt
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Triangulate_hole_polygon_mesh.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polygon_mesh.h
similarity index 98%
rename from Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Triangulate_hole_polygon_mesh.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polygon_mesh.h
index a5bb5bdbead..3e6dfa234d8 100644
--- a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Triangulate_hole_polygon_mesh.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polygon_mesh.h
@@ -1,7 +1,7 @@
 #ifndef CGAL_HOLE_FILLING_TRIANGULATE_HOLE_POLYHEDRON_3_H
 #define CGAL_HOLE_FILLING_TRIANGULATE_HOLE_POLYHEDRON_3_H
 
-#include <CGAL/internal/Hole_filling/Triangulate_hole_polyline.h>
+#include <CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polyline.h>
 #include <CGAL/Timer.h>
 #include <CGAL/trace.h>
 #include <CGAL/boost/graph/iterator.h>
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Triangulate_hole_polyline.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polyline.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Triangulate_hole_polyline.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polyline.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Weights.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Weights.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Hole_filling/Weights.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/Weights.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Hole_filling/experimental/experimental_code.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/experimental/experimental_code.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Hole_filling/experimental/experimental_code.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Hole_filling/experimental/experimental_code.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Meshing_functions/Fair_Polyhedron_3.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Meshing_functions/Fair_Polyhedron_3.h
similarity index 98%
rename from Polygon_mesh_processing/include/CGAL/internal/Meshing_functions/Fair_Polyhedron_3.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Meshing_functions/Fair_Polyhedron_3.h
index 3c3c9de1f44..d2cdb232f00 100644
--- a/Polygon_mesh_processing/include/CGAL/internal/Meshing_functions/Fair_Polyhedron_3.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Meshing_functions/Fair_Polyhedron_3.h
@@ -4,7 +4,7 @@
 #include <map>
 #include <set>
 #include <CGAL/assertions.h>
-#include <CGAL/internal/Hole_filling/Weights.h>
+#include <CGAL/Polygon_mesh_processing/internal/Hole_filling/Weights.h>
 #include <CGAL/Timer.h>
 #include <CGAL/trace.h>
 
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Meshing_functions/Refine_Polyhedron_3.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Meshing_functions/Refine_Polyhedron_3.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Meshing_functions/Refine_Polyhedron_3.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Meshing_functions/Refine_Polyhedron_3.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/AABB_triangle_accessor_3_primitive.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/AABB_triangle_accessor_3_primitive.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/AABB_triangle_accessor_3_primitive.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/AABB_triangle_accessor_3_primitive.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h
similarity index 96%
rename from Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h
index 6ff1e603807..a02138e332a 100644
--- a/Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Point_inside_vertical_ray_cast.h
@@ -22,7 +22,7 @@
 #ifndef CGAL_POINT_INSIDE_POLYHEDRON_POINT_INSIDE_VERTICAL_RAY_CAST_H
 #define CGAL_POINT_INSIDE_POLYHEDRON_POINT_INSIDE_VERTICAL_RAY_CAST_H
 
-#include <CGAL/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h>
+#include <CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h>
 #include <CGAL/point_generators_3.h>
 #include <CGAL/Origin.h>
 
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Point_inside_polygon_mesh/Ray_3_Triangle_3_traversal_traits.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h
diff --git a/Polygon_mesh_processing/include/CGAL/internal/Polygon_mesh_slicer/Traversal_traits.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Traversal_traits.h
similarity index 100%
rename from Polygon_mesh_processing/include/CGAL/internal/Polygon_mesh_slicer/Traversal_traits.h
rename to Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Traversal_traits.h
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/refine.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/refine.h
index cc5db2682b5..6c473a67f7e 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/refine.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/refine.h
@@ -1,7 +1,7 @@
 #ifndef CGAL_POLYGON_MESH_PROCESSING_REFINE_H
 #define CGAL_POLYGON_MESH_PROCESSING_REFINE_H
 
-#include <CGAL/internal/Meshing_functions/Refine_Polyhedron_3.h>
+#include <CGAL/Polygon_mesh_processing/internal/Meshing_functions/Refine_Polyhedron_3.h>
 
 namespace CGAL {
 
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_slicer.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_slicer.h
index ddfd884ecab..bc5ce6adc52 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_slicer.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_slicer.h
@@ -31,8 +31,8 @@
 
 #include <boost/foreach.hpp>
 #include <boost/graph/adjacency_list.hpp>
-#include <CGAL/internal/Polygon_mesh_slicer/Traversal_traits.h>
-#include <CGAL/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h>
+#include <CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Traversal_traits.h>
+#include <CGAL/Polygon_mesh_processing/internal/Polygon_mesh_slicer/Axis_parallel_plane_traits.h>
 
 #include <boost/variant.hpp>
 
diff --git a/Polygon_mesh_processing/include/CGAL/triangulate_hole.h b/Polygon_mesh_processing/include/CGAL/triangulate_hole.h
index d46fb6d4664..e2e5c9f4b4f 100644
--- a/Polygon_mesh_processing/include/CGAL/triangulate_hole.h
+++ b/Polygon_mesh_processing/include/CGAL/triangulate_hole.h
@@ -1,8 +1,8 @@
 #ifndef CGAL_TRIANGULATE_HOLE_H
 #define CGAL_TRIANGULATE_HOLE_H
 
-#include <CGAL/internal/Hole_filling/Triangulate_hole_polygon_mesh.h>
-#include <CGAL/internal/Hole_filling/Triangulate_hole_polyline.h>
+#include <CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polygon_mesh.h>
+#include <CGAL/Polygon_mesh_processing/internal/Hole_filling/Triangulate_hole_polyline.h>
 #include <CGAL/Polygon_mesh_processing/refine.h>
 #include <CGAL/Polygon_mesh_processing/fair.h>
 #include <CGAL/Default.h>