Prominent among the literary, scientific, and art institutions of Mexico City are the Geographical Society, the oldest of all, founded in 1833; the Geological Society; the Association of Engineers and Architects; Society of Natural History; the five Academies of Medicine, Jurisprudence, Physical and Natural Science, Spanish Language, Social Science, respectively; also the Antonio Alzate Scientific Society and the Pedro Escobedo Medical Society. Of museums and galleries are the Academy of San Carlos, with fine specimens of European and Mexican art, among the former of which are works by Velasquez, Murillo, Ribera, and others attributed to Rubens, Leonardo da Vinci, Van Dyck, &c. The National Museum, which was founded in 1865, is an important and interesting institution, in which are preserved the famous archaeological and ethnological objects and collections illustrative of prehistoric Mexico. It was founded in 1865, and attracts Mexican and foreign visitors to the annual number of nearly a quarter of a million. The famous prehistoric Calendar Stone is preserved here.[30] There are various other museums devoted to special subjects. Of libraries, the _Biblioteca Nacional_ ranks first--a handsome building with 365,000 volumes for public use. The building is a massive stone structure, and was originally built for a church. A garden surrounds it, and upon the stone pillars of the enclosure are busts of Mexicans and Aztecs famous in history, as Ixtlilxochitl, Tezozomoc, Nezahualcoyotl, the king-poet; Clavijero, the historian, and others. Other libraries are maintained by various museums and professions. [Footnote 30: Also the Aztec sacrificial stone.] There are some sixty or more Catholic churches in the city, and numerous other buildings formerly of ecclesiastical purpose. Most of these were built during the colonial _regime_, the Spanish Renaissance being the prevailing style. Several Protestant places of worship exist--religious observance being absolutely free--and these include Episcopalians, Presbyterians, Methodists, Baptists, and others. The religious census, made in 1900, of the whole of the Republic gave thirteen and a half million persons declaring themselves as Catholics, about 52,000 Protestants, 1,500 Mormons, 2,000 Buddhists, and about 19,000 who made no statement of religious faith.