With a capacity of 12,500, the building was at the time of its opening the second largest in America to Madison Square Garden. Initially, the venue was configured and equipped to hold numerous kinds of events including theater, opera, conventions, sporting events, exhibitions, concerts, and more. Renovations were made to the building in the 1940s, and in 1953 the southern half of the building was converted into the Auditorium Arena, a pure sporting venue with seating capacity of 6,841.
It hosted the ABA's Denver Rockets, later the Denver Nuggets, from 1967 until they left for McNichols Sports Arena in 1975. The Auditorium Arena was an annual host of the Colorado high school state basketball tournament, primarily for the smaller-enrollment classifications.