The apartment building, or simply the building, refers to the apartment building at 2311 North Los Robles Avenue, Pasadena, California. When viewed from the satellite photographs in "The Countdown Reflection" episode it appears to be located at 215 South Madison Avenue. Leonard, Sheldon, and Penny occupy apartments on the fourth floor. Adjacent to a lamp store, it is located about a block from Pasadena City Hall, which is visible through Sheldon and Leonard's window. The building is also located near a Chevron station on Colorado Boulevard, because Leonard makes the excuse that he uses its bathroom when he and Penny began seeing each other for the second time in season 5.