Hanging Rock, also known as Overhanging Rock, or locally as Drummond's head, is a historic natural feature which is located in Gulph Mills, Upper Merion Township, Montgomery County, Pennsylvania.

It is a large natural outcropping of phyllite that protrudes approximately eight feet over a roadway,[2] Pennsylvania Route 320 (South Gulph Road), which was laid out as a public highway between 1711 and 1712.

It was subsequently used by General George Washington and the Continental Army to move troops into Valley Forge for the winter encampment of 1777–1778.

[3] The rock formation was dedicated as a memorial to that march by the Valley Forge Historical Society in 1924.

[2] In January 2020, PennDot started a project to realign Route 320 (South Gulph Road) away from Hanging Rock, which had protruded into the roadway, resulting in limited sight distances; the project was completed in June 2022.