/usr/include/CGAL/Arrangement_2/ is in libcgal-dev 4.5-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Arrangement_2/Arr_compute_zone_visitor.h
/usr/include/CGAL/Arrangement_2/Arr_default_planar_topology.h
/usr/include/CGAL/Arrangement_2/Arr_do_intersect_zone_visitor.h
/usr/include/CGAL/Arrangement_2/Arr_on_surface_with_history_2_impl.h
/usr/include/CGAL/Arrangement_2/Arr_traits_adaptor_2.h
/usr/include/CGAL/Arrangement_2/Arr_traits_adaptor_2_dispatching.h
/usr/include/CGAL/Arrangement_2/Arr_with_history_accessor.h
/usr/include/CGAL/Arrangement_2/Arrangement_2_iterators.h
/usr/include/CGAL/Arrangement_2/Arrangement_on_surface_2_global.h
/usr/include/CGAL/Arrangement_2/Arrangement_on_surface_2_impl.h
/usr/include/CGAL/Arrangement_2/Arrangement_zone_2_impl.h
/usr/include/CGAL/Arrangement_2/Open_hash.h
/usr/include/CGAL/Arrangement_2/arrangement_type_traits.h