The University of Wisconsin Armory and Gymnasium, also known as the Red Gym or Old Red, is located along the shore of Lake Mendota at the eastern edge of the University of Wisconsin campus. In 1881 the university's President, John Bascom, began lobbying for a gymnasium that could be used for both military drill and gymnastic exercises. At the time, physical education, especially for male students, was becoming an important part of the university's curriculum. However, it was not until March 12, 1891 that the Legislature approved the bill allowing the armory and gymnasium to be built. The cornerstone was laid on June 20, 1893 and the Armory was opened in May 1894.

The regionally prominent architectural firm of Conover and Porter designed the Romanesque Revival Style building. The Armory's design is distinguished by stepped gables, turrets and towers with corbelled and crenellated battlements and broad arched entryways on the south and west facades. The Armory features a rusticated, coursed, sandstone ashlar foundation and red brick walls with sandstone trim.

From the outset, the Armory was used for more than university athletic and military functions. Everything from university dances and banquets to organized viewings of away-football games were held in the Armory's drill hall. The drill hall was also frequently used for political events. An 1894 rally, featuring U.S. President William McKinley, was its first political use. In 1904 the Armory was the site of the controversial Wisconsin Republican Convention. At the convention Robert M. La Follette's Progressive party won control of the Wisconsin Republican Party. The Progressive's victory eventually led to the enactment of substantial reforms throughout Wisconsin. The 1904 "Gymnasium Convention" holds national significance in the history of the Progressive Movement.

Today the Armory is part of the large University of Wisconsin campus. It contains a visitors' center and is open to the public during regular school hours.