Mary Ann Hall was an entrepreneur who while still in her 20's built a large house at 349 Maryland Avenue (now the site of the Native American Museum) where she operated what was to become the biggest and best brothel in the city. Her brothel was in a convenient location near the U.S. Capitol Building in a city known for its large population of transient men who came from all over the country, usually unaccompanied by women, to transact business in the national capital. Hall probably operated her establishment in a manner similar to the high-class "parlor houses" common in New York City at the time. The typical parlor house served men of wealth and distinction in a discreet and elegant environment, each transaction beginning with a shared bottle of champagne provided, at an exorbitant price, by the house. The prostitutes who worked in these houses were noted for their youth, beauty, and social refinement. With the outbreak of the Civil War in 1861, the sleepy town of Washington was dramatically transformed as its population swelled with newcomers. The new arrivals included many men who had signed up to fight for the Union. Along with the soldiers came government bureaucrats, freed and escaped slaves, businessmen, salesmen, and con men, as well as the camp followers and prostitutes who sought to profit from the increased demand for their services. The Army's provost marshal, who kept a list of the city's bawdy houses during the war ostensibly to keep them under surveillance, published a list of Washington's bawdy houses in 1864. Mary Ann Hall's first-class house, with 18 "inmates," employed far more prostitutes than any other brothel in the city, and it was rated by the provost marshal as the best.