The small and square gatehouse was built between 1899 and 1901 by the U.S. Army Corps of Engineers as an improvement and modernization of the water supply pipeline, first constructed in 1853. This effort was largely focused on reducing the annual typhoid epidemics that plagued Washington during summertime. The gatehouse, situated at the mouth of the Georgetown Reservoir, was built to pass water on the way through the four-mile-long city tunnel to the McMillan Reservoir and Treatment Plant. It played an important role in the preliminary stages of water filtration whereby debris is removed from the raw water; the structure included a metal gate that could stop incoming water flow.
Architecturally, the structure adopts the appearance of a turreted castle, the official insignia of the Corps, possibly patterned after one of the city gates of Verdun, France. The insignia was adopted in 1840 after the Revolutionary War due to the importance of castles in historical fortifications and a general sentimentality toward medieval forms. The Corps articulated that "in this country the term 'castle' has been applied to the strongest of our early fortifications, such as Castle Pinckney in Charleston, South Carolina, and Castles Williams and Clinton in New York Harbor." The gatehouse design is highly conventional, its symmetrical facades on all four sides are identical, without decoration or embellishment; the only distinctive features include turrets, crenellated parapets, rectangular blind openings, pointed arches at entryways, and an elevated base with steps that follow the perimeter of the building. The edifice employed brick as the structural material and Portland cement plaster, scored to replicate stonework. In 1958, the old stucco was removed and a new coat reapplied to preserve the same aesthetic effect. The gatehouse resembles Chicago’s Water Tower, which was built in 1869 by architect William W. Boyington and remained one of few buildings that survived the Great Chicago Fire of 1871. It was added to the National Register of Historic Places in 1975 and remains managed by the U.S. Army Corps of Engineers.
National Park Service. “Castle Gatehouse, Washington Aqueduct.” National Register of Historic Places Collection, 1975.
U.S. Army Corps of Engineers. The History of the US Army Corps of Engineers. Urbana-Champaign: University of Illinois, 1998.