Investors bought the Moulin Rouge Gardens property and spent one-million dollars to expand the facility. Opened in 1921, Mann's Million Dollar Rainbo Room, named after Fred Mann's wartime service in the U.S. Army's 42nd Infantry or "Rainbow" Division, was said to be the largest nightclub in America, featuring some of the biggest names in Vaudeville and musical entertainment. Larry Fine was performing there the night he was asked to join The Three Stooges. The Rainbo Room had a revolving stage to allow for continuous entertainment. There was table seating for 2,000 patrons and space on the dance floor for an additional 1,500. Until 1927, WMAQ radio shared the 670 kilohertz frequency with station WQJ, which was owned by the Rainbo and Calumet Baking Powder Company; it broadcast music of the Rainbo's performers as a form of promotion.