Chapultepec Park houses the Chapultepec Castle, now a museum on a hill that overlooks the park and its numerous museums, monuments and the national zoo and the National Museum of Anthropology (which houses the Aztec Calendar Stone). Another piece of architecture is the Fine Arts Palace, a white marble theatre/museum whose weight is such that it has gradually been sinking into the soft ground below. Its construction began during the presidency of Porfirio Díaz and ended in 1934, after being interrupted by the Mexican Revolution in the 1920s. The Plaza of the Three Cultures in the Tlatelolco neighbourhood, and the shrine and Basilicas of Our Lady of Guadalupe are also important sites. There is a double-decker bus, known as the "Turibus", that circles most of these sites, and has timed audio describing the sites in multiple languages as they are passed.