Sometimes dubbed the “fort that saved America,” this site is one you probably didn’t learn about in history class. Built by the British in 1771 to protect the wealthy colonial city of Philadelphia, Fort Mifflin was in American hands when the seeds of revolution took root.

As General George Washington suffered a series of defeats in the Philadelphia Campaign in the fall of 1777, he recognized the importance of disrupting the supply route for the British army occupying Philadelphia. Washington ordered the garrison at the little fort to “hold to the last extremity” as they faced off against the mightiest navy of the 18th-century world.

Ultimately surrounded on three sides and out of ammunition and black powder, the garrison evacuated to Fort Mercer. A detail of 40 young soldiers remained behind to spike the last 10 functioning cannons and set fire to any valuable remains. They left the distinctive 13-stripe flag flying as they, too, finally rowed away from the burning fort. Although defeated, Fort Mifflin never surrendered. General Washington used the time to establish winter quarters at Valley Forge emerging the following spring better trained and organized, and with the official support of France.

The fort was rebuilt beginning in the late 18th century and as part of the First and Second Systems of Seacoast Fortifications answered every call to service over three centuries. As such, one visit to Fort Mifflin lets you stand on a Revolutionary War battlefield, in a Civil War prison, and on the site of a “home front” defense in World War II.

Perhaps because of the many hardships suffered there, the Fort is also on just about every list of the most haunted locations in the country. Visitors can explore the Casemates (bomb-proof shelters) featured on Ghost Hunters and many buildings and magazines to decide if there are any spooky permanent residents lingering within the site.