Prospectville is a populated place on the northwestern end of Horsham Township, a home rule municipality of Montgomery County, Pennsylvania, United States.

[citation needed] Prospectville, established at the junction of Limekiln Pike and Horsham Road, was originally known as Cashtown.

This portion of Limekiln Pike was an extension of the original segment established in 1693 to provide a thoroughfare between Old York Road and the lime kilns of Thomas Fitzwater in Upper Dublin Township.

Here lived several generations of the Simpson family, one of whom was the mother of Ulysses S. Grant, the 18th President of the United States.

The mansion has remained virtually intact since the late 18th century and it is the only National Historic Landmark within Horsham Township.