 A number of structures are included in an historic district listed on the National Register of Historic Places, including the two concrete casemates for the 16"/50 caliber M1919 guns of Battery Harris.Fort Tilden is an important nesting area for the threatened Piping Plover, a species which NPS—as part of a large global effort—is working to protect.The eggs and chicks are very small and highly camouflaged, so they are extremely difficult to see.