U.S. Customhouse

New Orleans was the largest port in the Southern United States throughout the 19th century, exporting most of the nation's cotton output and other farm products to Western Europe and New England. Every bale, barrel, and cask passed through this building — a fortress-scale customhouse that took 33 years to finish, longer than any other federal building of its era. Construction began in 1848 under architect Alexander Thompson Wood, who died before completion. The Civil War halted work for five years. During the occupation of New Orleans, General Benjamin Butler claimed the unfinished building as Union headquarters. When the granite and marble finally stopped rising in 1881, the Customhouse occupied an entire city block at 423 Canal Street. The Marble Hall runs 128 feet long, 84 feet wide, and 54 feet high. Fourteen white marble columns hold up a skylight ceiling. This is the room where clerks tallied the flow that made New Orleans what it was — the cotton that fed Lancashire mills, the sugar bound for Boston refineries, the coffee headed to New York docks. The largest city in the South at the start of the Civil War built a customhouse to match the scale of what moved through it. The building now houses the Audubon Insectarium. Open daily. Walk the Marble Hall and you're standing in the accounting room of an empire's supply line.