Europe, the United States, and Latin America. The Perry–Castañeda Library, which houses the central University Libraries operations and the Perry–Castañeda Library Map Collection, is at the heart of campus. The Benson Latin American Collection holds the largest collection of Latin American materials among US university libraries, and maintains substantial digital collections. The University of Texas at Austin has an extensive tunnel system that links the buildings on campus. Constructed circa 1928 under the supervision of UT engineering professor Carl J. Eckhardt Jr., then head of the physical plant, the tunnels have grown along with the campus. They measure approximately six miles in length. The tunnel system is used for communications and utility service. It is closed to the public and guarded by silent alarms. Since the late 1940s, the university has generated its own electricity. Today its natural gas cogeneration plant has a capacity of 123 MW. The university also operates a TRIGA nuclear reactor at the J. J. Pickle Research Campus. The university continues to expand its facilities on campus. In 2010, the university opened the state-of-the-art Norman Hackerman building (on the site of the former Experimental Sciences Building) housing chemistry and biology research and teaching laboratories. In 2010, the university broke ground on the $120 million Bill & Melinda Gates Computer Science Complex and Dell Computer Science Hall and the $51 million Belo Center for New Media, both of which are now complete. The new LEED gold-certified, Student Activity Center (SAC) opened in January 2011, housing study rooms, lounges and food vendors. The SAC was constructed as a result of a student referendum passed in 2006 which raised student fees by $65 per semester. In 2012, the Moody Foundation awarded the College of Communication $50 million, the largest endowment any communication college has received, so naming it the Moody College of Communication. The university operates two public radio stations, KUT with news and information, and KUTX with music, via local FM broadcasts as well as live streaming audio over the Internet. The university uses Capital Metro to provide bus transportation for students around the campus on the UT Shuttle system and throughout Austin. Organization and administration The university contains eighteen colleges and schools and one academic unit, each listed with its founding date: Cockrell School of Engineering (1894) Dell Medical School (2013) College of Education (1905) College of Fine Arts (1938) College of Liberal Arts (1883) College of