The initial design for the station was created in 1882 by McKim, Mead & White. Had the original plan been built, the station would have been the largest train station in the world. A smaller plan was introduced by architects Van Brunt & Howe, and accepted in 1885. Construction of the station began in 1890. It was built by Northern Pacific Terminal Company at a cost of $300,000, and opened on February 14, 1896. The signature piece of the structure is the 150 ft. tall Romanesque Revival clock tower. Neon signs were added to the tower in 1948. The signs read "Go by Train" on the northeast and southwest sides and "Union Station" on the northwest and southeast sides.