Fort Warren is a historic fort on the 28-acre (110,000 m2) Georges Island at the entrance to Boston Harbor. The fort is named for Revolutionary War hero Dr. Joseph Warren, who sent Paul Revere on his famous ride, and was later killed at the Battle of Bunker Hill. The name was transferred in 1833 from the first Fort Warren – built in 1808 – which was renamed Fort Winthrop.

Georges Island is one of the islands in the Boston Harbor, situated just over 7 miles (11 km) from downtown Boston. The island has a permanent size of 39 acres (160,000 m2), plus an intertidal zone of a further 14 acres (57,000 m2), and rises to a height of 50 feet (15 m) above sea level. Historic Fort Warren is on the island. Because of this, and since a ferry operates from Boston to the island, it is a popular destination and one of the easiest islands to access in the Boston Harbor Islands National Recreation Area.