Further major construction largely ceased on the site until the groundbreaking for the College of Humanities Arts and Social Sciences (CHASS) in April 1951. A group of five buildings designed by different architects in a decidedly more Modern style were completed by 1954: the Rivera Library, Webber Hall, Geology Building, Physical Education Building and Watkins Hall. After the Regents declared UCR a "general campus" of the UC system in 1958, many new buildings and additions were laid out over the following decade. Following an east–west axis, new student residence halls and athletic facilities were developed along the southeastern quadrant of the main campus, while academic and research facilities were built along the central campus area closer to the freeway. The Bell Tower, one of only five carillons in California, was built in this period. Designed by A. Quincy Jones, the tower is tall and contains 48 bells, each weighing from to , covering four chromatic octaves.