Halcyon House, Federal mansion in Georgetown, Washington D.C., United States.
The three-story brick residence spans 21,000 square feet, featuring symmetrical windows, a grand entrance, and gardens near the Potomac River.
Benjamin Stoddert, the first Secretary of the Navy, constructed this residence in 1787 and hosted numerous social gatherings of early American leaders.
The mansion contains architectural elements from different periods, including original Federal designs and modifications from the early twentieth century.
Located at 3400 Prospect Street NW, the property now serves as headquarters for Halcyon, an organization supporting science and entrepreneurial initiatives.
Albert Clemens, Mark Twain's nephew, added unusual features such as staircases leading nowhere, believing continuous construction would extend his life.
Location: Washington, D.C.
Inception: 1787
Architectural style: Federal architecture
GPS coordinates: 38.90575,-77.06806
Latest update: September 23, 2025 14:24
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