Río Piedras is a highly urbanized commercial and residential district in San Juan, the capital municipality of Puerto Rico, concentrated in the barrios of Pueblo, Universidad, Hato Rey Sur, El Cinco, and Monacillo Urbano, about 4 to 7 miles from the Old San Juan historic quarter, Condado and Isla Verde resort areas, and SJU airport. The district, which was the downtown center of a former municipality with the same name that was merged with San Juan in 1951, has been the home of the main campus of the University of Puerto Rico since 1903, earning the popular name of Ciudad Universitaria. The largest health institution in the archipelago and island, the Centro Médico de Puerto Rico, is also located within Río Piedras.