Grumblethorpe was built as a summer residence in 1744 by Philadelphia merchant and wine importer John Wister. In September 1777, the house was the scene of events in the Battle of Germantown. While the Wisters were staying in another home, British General James Agnew occupied the house as his headquarters during the battle. He was wounded and died in the front parlor, where his blood stains can still be seen on the floor. The home is a National Historic Landmark.