The Arizona-Sonora Desert Museum is the single best introduction to the Sonoran Desert and probably the most rewarding sight in Tucson after the Mission. It is part zoo, part botanical garden, part natural-history museum — but all of it outdoors, on a 98-acre site in the Tucson Mountains, with the saguaro forest stretching out around you.
The exhibits walk you through every ecosystem of the desert: mountain woodland, cactus garden, hummingbird aviary, an underground tunnel of cave-dwellers, a riparian zone with otters, and the new stingray touch tank. Twice a day in winter, the staff fly raptors free over the grounds. Allow at least four hours. Open at 7:30am in summer — go early to beat the heat. Combine with Saguaro National Park West just up the road.