Beck's objective, in his own words, was to make the Orpheum Circuit bring the highest forms of art within the reach of the people with the slimmest purses. He quickly decided to construct a junior Orpheum theater in downtown Kansas City, employing the Chicago architectural firm of Rapp and Rapp. Unusually for the time, the structure had a cooling system that made the building comfortable even in the summer months. The theater even provided, for parents who wanted a night out without worrying about their offspring, a free nursery in the building, complete with a trained nurse and assistants. Featured live acts included Charlie Chaplin, Cab Calloway and the Marx Brothers.
The design of the Mainstreet Theater was similar to other Rapp and Rapp theaters, such as the Chicago and Tivoli Theaters, in that a monumental arch was employed at the main entrance. The rusticated terracotta and brick building differed from those other designs, however, due to two distinctive features: the Byzantine dome at the entrance, embellished with golden tiles, and the storefronts lining the building's east facade.
Although films were beginning to outstrip vaudeville in popularity, Beck, a lover of live theater, resisted, and for that and other reasons, he was ousted from his position as Orpheum's president. (He went on to construct and manage the Martin Beck Theater in New York, now known as the Al Hirschfeld Theater.) The Mainstreet began to show films, but during the Depression, it was difficult for such a large theater to maintain an audience, even with a 10-cent admission charge. In 1938, it partially closed, then closed completely until 1949, when it was refurbished and reopened as the R-K-O Missouri. This theater had the historic distinction of showing the first 3-D movie in Kansas City. In the mid-1950s, the Missouri installed the complicated and expensive Cinerama process to attract a new audience, but the novelty of this widescreen technology soon faded, and the theater closed yet again.
In the 1960s, it opened under a new name - the Empire - with a much reduced seating capacity: only 1200 seats. The Empire was eventually split into a multiplex with four separate theaters, but still could not remain viable. In October, 1985, AMC, its owners, closed it for the third time, and it remained so for over 20 years. The developer who purchased the property wanted to demolish the Empire and build office space, leaving only the dome, but the City of Kansas City resisted and bought the property in 2004. On May 1, 2009, AMC, which partnered with a local developer, reopened the theater as part of the Power & Light District as the AMC Mainstreet Theater (restoring its original name). A reported $30 million was spent on the restoration. In May, 2009, the theater was awarded the Dr. George Ehrlich Achievement in Preservation Award by the Historic Kansas City Foundation.
The building was purchased from AMC by Alamo Drafthouse, which runs it today under the name Alamo Drafthouse Mainstreet. The theater combines film screenings with in-theater dining to provide a novel moviegoing experience. It also hosts special events, in some of which the actors who appear in the films being screened show up in person to interact with audiences: a curious revival of its live theater tradition. On the blog The Noir Factory, the Alamo Drafthouse Mainstreet was voted one of the 12 best theaters in America to view film noir movies.