Fort Carroll Light is a derelict lighthouse consisting of a short wooden tower on the walls of its namesake fortifications in the Patapsco River. The construction of Fort Carroll beginning in 1847 set a large new hazard to navigation immediately adjacent to the ship channel, and a keeper's house with a light tower on it was constructed in 1854. At the time, the light …Fort Carroll Light is a derelict lighthouse consisting of a short wooden tower on the walls of its namesake fortifications in the Patapsco River. The construction of Fort Carroll beginning in 1847 set a large new hazard to navigation immediately adjacent to the ship channel, and a keeper's house with a light tower on it was constructed in 1854. At the time, the light keeper was the only resident of the artificial island.