Dupont Circle is located in the "Old City" of Washington, D.C.—the area planned by architect Pierre Charles L'Enfant—but remained largely undeveloped until after the American Civil War, when there was a large influx of new residents. The area that now constitutes Dupont Circle was once home to a brickyard and slaughterhouse. There also was a creek, Slash Run, that began near 15th Street NW and Columbia Road NW, ran from 16th Street near Adams Morgan, through Kalorama and within a block of Dupont Circle, but the creek has since been enclosed in a sewer line. Improvements made in the 1870s by a board of public works headed by Alexander "Boss" Shepherd transformed the area into a fashionable residential neighborhood.