The Mercantile National Bank Building is a 31-story, 159.4 m (523 ft) skyscraper at 1800 Main Street in the Main Street district of downtown Dallas, Texas. It is the former home of the Mercantile National Bank, which later became MCorp Bank. The design of the skyscraper features Moderne styling from the Art Deco era and was designed by Walter W. Ahlschlager. The building has a series of setbacks that is crowned by an ornamental four-sided clock along with a decorative weather spire. The Merc was the main element of a four-building complex that eventually spanned a full city block.