When people are visiting Philadelphia, they often hit the historical hot spots. Fort Mifflin is one of Philadelphia's best kept secrets. It’s known as The Fort That Saved America because it was one of three forts responsible for keeping the British forces occupied long enough for General George Washington to march his Continental Army into Valley Forge to properly train them. This building is the Officer's Quarters. Although no one has been inside for years, the building is very active in the paranormal realm and has even been featured on Ghost Hunters.