In 1926 the Riles Building, originally known as the College Gymnasium, became the first indoor athletic facility at Arizona State Teachers College at Flagstaff. The building's architecture is an example of the Colonial Revival style, most prominently characterized by the keystone at the top of the main entrance arch.
The Gymnasium housed a basketball court with an indoor swimming pool underneath the floor, the first of its kind in northern Arizona. During World War II the College allowed the V-12 program to use the gym as a firing range. After the war, it became the Women's Gymnasium and housed women's physical education until the 1970s. A 1983 remodeling transformed the space into offices and classrooms. In 1987, Northern Arizona University named the building after Wilson Riles, the first African-American student in the institution's history. Riles earned his bachelor's degree in education in 1940.
Today the Riles Building houses the College of Arts and Letters and Comparative Cultural Studies. The women’s athletic teams now practice at the Skydome on south campus, the University Union Fieldhouse, and the J.C. Rolle Activity Center.