The Merchandise Mart (or the Merch Mart, or the Mart) is a commercial building located in the Near North Side of Chicago, Illinois, United States. When it opened in 1930, it was the largest building in the world, with 4,000,000 square feet (372,000 m2) of floor space.The art deco landmark is located at the junction of the Chicago River's branches. The building is a leading retailing and wholesale destination, hosting 20,000 visitors and tenants per day as of the late 2000s.