Old Stone House (Georgetown's 18th-century dwelling)

The Old Stone House at 3051 M Street NW is the oldest unchanged building in Washington, D.C., with construction dated to the mid-18th century (commonly cited as 1765). The three-story stone townhouse survives from pre‑city Washington and is preserved as a historic house museum administered by the National Park Service. It illustrates colonial domestic architecture within the Georgetown neighborhood and remains on its original foundation and location.