At the time of this publication, Harmony Hall was closed to the public. Please check the park website for updated information. Harmony Hall is in the Broad Creek Historic District, the first historic district formed under Prince George's County preservation law. The house is an 18th century Georgian country house that architecturally ranks as one of the great early plantation houses and an outstanding early colonial house of Maryland. The front of the house faces the Potomac River and remains much as it appeared in 1766, the estimated time of construction.