38°45′40″N 77°07′12″W / 38.761°N 77.120°W Okeley Manor was an early 19th-century plantation in Fairfax County, Virginia, United States. Okeley, the residence of prominent Alexandria physician Richard Chichester Mason (1793–1869), was one of the principal Mason family estates in Northern Virginia.[1] Mason's plantation house was used as a hospital during the American Civil War and burned to prevent the spread of smallpox.