High Quality Content by WIKIPEDIA articles! The Colonial Germantown Historic District is a designated National Historic Landmark District in the Germantown and Mount Airy neighborhoods of Philadelphia, Pennsylvania along both sides of Germantown Avenue. This road followed an Indian path from the Delaware River just north of Old City Philadelphia, through Germantown, about 6 miles northwest of Center City Philadelphia, and on to Pottstown. Settlement in the Germantown area began, at the invitation of William Penn, in 1683 by Nederlanders and Germans under the leadership of Francis Daniel Pastorius fleeing religious persecution.