[9] Major Thomas married Anne Ridgely,[11] who was raised at an earlier estate named Montpelier in Fulton, Maryland, and built the Mansion circa 1783.

(His son Nicholas N. Snowden, also born at the mansion, became a farmer next to Avondale Mill, and died at Manassas while serving in the 1st Maryland Infantry, CSA.

[16] Long's daughter Christine L. Willcox, the mansion's last private owner,[17] donated the property to the Maryland-National Capital Park and Planning Commission in 1961.

The historic home was opened as a public tourist attraction in 1985,[19] reflecting its ownership by Nicholas Snowden[5] in 1830.

The mansion can be rented for conferences and weddings and the grounds serve as a cultural center, hosting special exhibitions and performances.

The two-story central block has a five-bay elevation, with a projecting three-bay pavilion topped by a pediment.

The front and rear doors are similar in character, with flanking pilasters and an open pediment The interior features carved woodwork.