Construction of Fort Carroll began in 1847 to protect Baltimore Harbor, and in 1850 the fort was named for Charles Carroll, the last living signer of the Declaration of Independence. Congress provided $1,500 in 1852 for a lighthouse there, and in 1854 a temporary wooden tower lighthouse was built on the fort's unfinished parapet to warn ships of the construction site and indicate the path from Brewerton Channel to Fort McHenry Channel. Equipped with a fifth-order lens that produced a fixed white light and fog bell, this first temporary lighthouse had Martin Kasson as its first keeper and the fort's only resident at that time. In 1875 a new wooden tower was constructed and fitted with the lens and fog bell from the original lighthouse, and in 1888 a two-story keeper's dwelling was built at a cost of approximately 1,000. In 1898 the lighthouse and fog bell tower were demolished to allow installation of gun batteries, and a temporary tower was built 100 feet north of the original location. In 1900 the present-day wooden tower was moved 100 feet south because of additional fort modifications. Fort Carroll and the lighthouse stand on a man-made island in the Patapsco River, southeast of the Francis Scott Key Bridge and across from the Hawkins Point Lighthouse at Fort Armistead. In 1921 the U.S. Army abandoned the fort and the light was automated. During World War II, the fort served as a firing range and as temporary quarters for sailors whose ships had to be fumigated before entering the harbor. The U.S. Government sold the fort for $10,000 in 1958. The lighthouse received various repairs in 1964 and was vandalized one month later. In 1965 the lighthouse was taken out of service and replaced by a buoy. Since 1994 it has been on the Lighthouse Digest Doomsday List.