Horsham Township began as a farming and residential community. Today, the Willow Grove Naval Air Station is Horsham's largest employer and its most recognized feature. The predecessor of the air station was the Pitcairn Airfield. Here, Harold Pitcairn built the Mailwing airplane, delivered airmail along the East Coast, formed Eastern Air Lines, developed the Autogiro, and entertained celebrities such as Charles Lindbergh and Amelia Earhart. Photographs in Horsham Township show the Quaker meetinghouse, which is the oldest religious building in Horsham and is still in continuous use; the highways that served the township farmers, such as Limekiln Pike, York Road, and Easton Road; and the trolley cars from Doylestown to Willow Grove that connected the township to Philadelphia.