^Castle Gatehouse, Washington Aqueduct is a pumping station at the Georgetown Reservoir on the Washington Aqueduct in The Palisades neighborhood of Washington, D.C., United States. The building is on the National Register of Historic Places and contributes to the Washington Aqueduct National Historic Landmark.
In 1852 the United States Congress authorized the Army Corps of Engineers to construct a water supply for the city of Washington, using the Potomac River at Great Falls as its source. Construction of a 12-mile pipeline began in 1853, and portions of the system began operation in 1859.
Construction of the gatehouse began in 1899. The design was intended to replicate the Army Corps insigna. Portland cement plaster was used to replicate stonework and give the gatehouse an authentic castle appearance.
The gatehouse was added to the National Register of Historic Places on March 13, 1975. It is managed by the Army Corps of Engineers, Baltimore District.