Below, the main facade is three bays wide, with a one-story flat-roofed porch supported by Doric columns.

An octagonal wooden powder-house similar to the one at Mount Vernon exists today and is supposed to have held powder stores during the Revolution.

Stone and timber cutting could also have been supervised nearby, as the surrounding meadows are laced with limestone outcroppings, and the property included ample woodland.

On February 23, 1800, Samuel Washington sold Happy Retreat, including the mansion and 100 acres (0.40 km2) of land, to Thomas Hammond.

After his purchase of Happy Retreat, Judge Douglass completed the plans for the central section of the house and built a three-story brick structure, connecting the two old Washington wings.

The house passed through the hands of a number of different owners, reverting to its original name of Happy Retreat, before its purchase by Mr. and Mrs. William Gavin in the 1960s.

In September 2014, the city of Charles Town began working toward purchasing the house to include it in its parks system.