The oldest flag quarters in the Navy, the history of the Mattapany residence begins well before construction of the present day home. Part of a 1,200-acre estate, Charles Calvert, Third Lord of Baltimore, and his wife, the widow Jane Sewall, built the original manor and accompanying out buildings sometime between 1666 and 1671. Situated a few hundred yards from the current structure, it soon became the political center for Southern Maryland, complete with an armory, jail and courthouse.