San Xavier was founded in 1692 by the Jesuit missionary and explorer Eusebio Kino at what was then the Indian village of Bac. It was Kino's Franciscan successors, though, who built the present church in the late 1700s. Historians believe that the friars used craftspeople and artists from Querétaro, Mexico, as well as local Indians, to help construct and decorate the building, which stood on the desert like a beacon. The friars ran out of money before they could finish one bell tower and decorate one of the largest rooms in the church, but the elaborate Mexican baroque exterior and vividly painted interior had the desired effect - to draw native people into the fold.
Two centuries of almost constant use, an earthquake, and several well-intentioned but poorly executed preservation projects took their toll on San Xavier. By the early 1980s, the church and the members of the Patronato decided to mount an intensive fund-raising campaign to give the building a state-of-the-art face-lift.
As it turns out, state of the art has often meant going back to ancient ways. On the exterior of the church, modern, nonporous stucco has been replaced by a centuries-old plaster recipe containing sand, lime, and juice from boiled prickly pear cactus. The new mixture lets moisture evaporate before it does damage to the church's brick-and-stone-rubble walls.
Inside San Xavier, an international team of conservators has been working each winter since 1992. Led by Paul Schwartzbaum - chief conservator of the Solomon R. Guggenheim Museum in New York, whose résumé includes advising on the restoration of the Sistine Chapel - the conservators have been painstakingly cleaning candle smoke and dust from the garments of saints and the faces of angels, repairing water damage, and stabilizing the frescoes and sculpted surfaces, one section at a time.
But perhaps the most important aspect of the effort has been the training of members of the Tohono O'odham Nation in conservation techniques. Although some things are still in short supply out here in the Sonoran Desert, the conservators are trying to make sure that the knowledge needed to keep San Xavier shining for another two centuries is not one of them.