Tucson is a desert city in southern Arizona ringed by mountain ranges and saguaro cactus. Saguaro National Park protects giant saguaro cacti on both sides of the city, the Arizona-Sonora Desert Museum pairs a zoo, botanical garden, and natural history museum in the desert west of town, and the University of Arizona anchors the city with research and Wildcat sports. Downtown Tucson mixes historic buildings with new restaurants, Fourth Avenue offers shops and music venues, and the Mission San Xavier del Bac, known as the White Dove of the Desert, stands south of the city as a Spanish mission.