The Mission San Xavier del Bac, on the Tohono O'odham San Xavier Reservation nine miles south of Tucson, is the oldest intact European structure in Arizona and one of the great pieces of Spanish colonial architecture in the United States. Whitewashed walls, a dome that catches the desert light, painted santos crammed into every niche, and ceilings of folk Baroque polychrome — even non-believers tend to stand still inside for a while.
The Tohono O'odham community still uses the church and runs the gift shop and food stalls outside; try a fry bread and a tamale from the women at the back. Climb the small hill across the parking lot for the classic view back at the mission against the desert. Admission is free; donations support an ongoing restoration that has been running for decades.