/usr/include/geos/geomgraph/ is in libgeos++-dev 3.5.0-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/geos/geomgraph/Depth.h
/usr/include/geos/geomgraph/DirectedEdge.h
/usr/include/geos/geomgraph/DirectedEdgeStar.h
/usr/include/geos/geomgraph/Edge.h
/usr/include/geos/geomgraph/EdgeEnd.h
/usr/include/geos/geomgraph/EdgeEndStar.h
/usr/include/geos/geomgraph/EdgeIntersection.h
/usr/include/geos/geomgraph/EdgeIntersectionList.h
/usr/include/geos/geomgraph/EdgeList.h
/usr/include/geos/geomgraph/EdgeNodingValidator.h
/usr/include/geos/geomgraph/EdgeRing.h
/usr/include/geos/geomgraph/GeometryGraph.h
/usr/include/geos/geomgraph/GraphComponent.h
/usr/include/geos/geomgraph/Label.h
/usr/include/geos/geomgraph/Node.h
/usr/include/geos/geomgraph/NodeFactory.h
/usr/include/geos/geomgraph/NodeMap.h
/usr/include/geos/geomgraph/PlanarGraph.h
/usr/include/geos/geomgraph/Position.h
/usr/include/geos/geomgraph/Quadrant.h
/usr/include/geos/geomgraph/TopologyLocation.h
/usr/include/geos/geomgraph/index/
/usr/include/geos/geomgraph/index/EdgeSetIntersector.h
/usr/include/geos/geomgraph/index/MonotoneChain.h
/usr/include/geos/geomgraph/index/MonotoneChainEdge.h
/usr/include/geos/geomgraph/index/MonotoneChainIndexer.h
/usr/include/geos/geomgraph/index/SegmentIntersector.h
/usr/include/geos/geomgraph/index/SimpleEdgeSetIntersector.h
/usr/include/geos/geomgraph/index/SimpleMCSweepLineIntersector.h
/usr/include/geos/geomgraph/index/SimpleSweepLineIntersector.h
/usr/include/geos/geomgraph/index/SweepLineEvent.h
/usr/include/geos/geomgraph/index/SweepLineEventObj.h
/usr/include/geos/geomgraph/index/SweepLineSegment.h