The Universidad de San Carlos de Guatemala (USAC, University of San Carlos of Guatemala) It is the biggest, most prestigious, and oldest university of Guatemala, also it is the fourth founded in the Americas. The transcendence of its students and itself has been seen in many important times, since the independence of Guatemala, Guatemalan Revolution, Guatemalan Civil War, and even today. The main campus is located on University City, zone 12 of Guatemala City, being the biggest one of Central America]]. It also has several extension branches on every region of the country, and a metropolitan center where the Medicine and Physiology Faculties operate. It was decreed a university on January 31, 1676 by royal command of King Charles II of Spain. It had previously been known as the Escuela de Santo Tomás (School of Saint Thomas), founded in 1562 by the priest Francisco Marroquín. The University finally gained international acceptance by Official Decree from Pope Innocent XI, on June 18, 1687. In the early years, from the 16th to 19th centuries, it offered studies in civil and liturgical law, theology, philosophy, medicine and indigenous languages.