Fort Carroll is a military garrison built on a small man-made island in the middle of the Patapsco River. The purpose of the hexagonal fort was to protect the city of Baltimore. The fort was abandoned after the end of World War I and is in extreme disrepair.
In this video the aerial footage is dated November 2014. If you look closely there appears to be some kind of animal moving in the upper window of the lighthouse, perhaps an owl.
YouTube link
(thanks Greg)
