Saturday marked the first broadcast day for KCBS- and KCAL-TV out of their new Valley studio in Studio City. The stations this weekend officially moved operations from CBS Columbia Square in Hollywood to the 162,000-square-foot, high definition studio at CBS Studio Center, 4200 Radford Ave. The building constructed on the northern portion of the back lot on a plot that once included the Big Brother house will house about 600 employees from the two stations and the West Coast operations of CBS News. The new studio was prompted after the stations had outgrown Columbia Square, which dates to 1938 and also had housed KNX-AM. It moved to new offices in the Miracle Mile in 2005. The shift means that all three major television networks have their West Coast flagships in the Valley. KABC-TV is based in Glendale and KNBC-TV is headquartered in Burbank. Read about the economic impact of the move here .