Fort Warren stands on Georges Island, a 39-acre harbor island situated seven miles from downtown Boston and accessible via public ferry or private boat. Constructed between 1833 and 1861, this star-shaped granite fortification was completed shortly after the Civil War began and is named for Revolutionary War hero Dr. Joseph Warren, who initiated Paul Revere's famous midnight ride. The fort served as a military training ground, patrol point, and notably as a humane Civil War prison, famously holding Confederate Vice President Alexander H. Stephens. Visitors can explore granite archways and stairways leading to the fort roof, which provides panoramic views of the Boston skyline and Massachusetts Bay during spring, summer, and fall.