National Mall

This guide to the National Mall in Washington, D.C. follows what used to run beneath this lawn: a marshy waterway called Tiber Creek, folded into the Washington City Canal in 1815 to connect the Potomac and the Anacostia. It also stops at Center Market, once the country's largest food hall, where over six hundred stalls sold live turtles tied to soap boxes and vendors haggled with presidents over produce. By the eighteen fifties, the guide notes, the canal was mostly dead weight, collecting the city's storm runoff.