The Cosmos Club (also known as the Townsend House; former residence of Richard H Townsend, Mary Scott Townsend, and Mathilde Townsend) located at 2121 Massachusetts Avenue, N.W., in the Dupont Circle neighborhood of Washington, D.C. Designed by the architectural firm of Carrère and Hastings in 1898, the Beaux-Arts building was listed on the National Register of Historic Places in 1973. It is designated as a contributing property to the Dupont Circle Historic District and the Massachusetts Avenue Historic District.