The Mercantile Exchange is a vibrant high-amenity multifaceted business district in Downtown St. Louis Missouri. The key to MX's success is it's superb location at the epicenter of where business, convention, tourism and entertainment intersect. Just a few blocks from the North Gateway of the Arch grounds and South of Washington Ave. between 6th and 7th Street. Office/Retail (1st and 2nd Floor Options) 926-5,301 SF. 750 Parking Spaces.