The Harold F. Pitcairn Wings of Freedom Aviation Museum in Horsham, Pennsylvania, preserves the history of flying in the Philadelphia region, especially NAS Willow Grove and aviation pioneer Harold F. Pitcairn. Opened to the public in 2004 and operated by the Delaware Valley Historical Aircraft Association, it grew from aircraft preservation efforts begun at Willow Grove after World War Two. Early display planes included a Curtiss TP-40N Warhawk, an Arado Ar 196, and other captured Axis aircraft, though many were later transferred to larger museums. Its collection includes restored aircraft, flight gear, missiles, ejection seats, and medals, and it has pursued expansion despite delays caused by hazardous chemicals on the former base.