For more than 200 years, visitors to what is now Southern Arizona have come upon a sight they could not quite believe: a gleaming cathedral of white that seems to float above the tan landscape like a mirage. Since its two towers first rose into the cloudless desert skies in the 1790s, San Xavier del Bac Mission church has been moving visitors to record the moment they saw it in wonder.

In 1793, Franciscan Friar Francisco Antonio Barbastro visited the Native community of Wa:k (incorrectly transcribed by the Spanish as “Bac”), which he described as “the northernmost village of the Christian world” and wrote, “The church which they are building … rivals the most beautiful churches in México. In this country it should rightly be termed ‘astounding.’”

Half a century later, United States Army Lieutenant Cave Johnson Couts, in the first known Anglo-American description, noted the sense of dislocation San Xavier del Bac can still inspire. “Its domes and spires which projected above the thick mesquite growth as we approached was of itself sufficient to guarantee a City with many churches and other large and fine buildings,” Couts wrote. “But when we came up, found it standing solitary and alone… .”

The church still rises out of the desert with the same ethereal majesty. But its solitary appearance is a trick of perspective. It has never been alone. Since the beginning, San Xavier del Bac has been part of a community of Native people now known as the Tohono O’odham. Still, the feeling of dislocation Couts recorded, of the mission belonging to another world than the one in which it had been placed, captures another truth: the long, often troubled history of Western settlement and Christian conversion in the Southwest.

How San Xavier del Bac and the people who love it, both Native and of European descent, have negotiated that history speaks to the power of preservation to create a common purpose. The mission survives today because the O’odham, the Roman Catholic Church, and the people of nearby Tucson have all, over the centuries, stepped up to make sure the building known as “The White Dove of the Desert” continues to beguile visitors. It’s an ongoing story that continues with the latest conservation work at San Xavier, which is being funded in part by a $250,000 capital grant from the National Fund for Sacred Places, a cooperative program of the National Trust for Historic Preservation and the nonprofit Partners for Sacred Places.

On a rare cloudy day this spring I climbed a narrow, vertiginous staircase inside the walls of the west tower at San Xavier del Bac, emerging onto the roof. While Bob Vint, the architect who has worked on the mission since 1989 and is currently in charge of restoring the east tower, discussed the work with construction managers nearby, I took in the view.

An arched expanse of startling white, defined by parapets with an elaborate set of finials marching toward the cross-topped dome on the north end of the building, greeted me. It all felt unexpectedly Middle Eastern, faintly Moroccan. In the 20 years I’ve lived in Tucson, I’ve visited the mission many times, but this was my first chance to climb up to the church’s bell tower and the roof. The impact was a more extreme version of my earlier impression of the place: awe-inspiring but disorienting.

In contrast to other Spanish missionaries, notably Junípero Serra in California, whose treatment of Native peoples led demonstrators to tear down his statues during last summer’s racial protests, Kino is by and large remembered fondly. Memorials to him abound in the Southwest, and his gravesite in the central plaza of the small city of Magdalena de Kino, Mexico, is a shrine.

But the peripatetic Kino was only in Bac off and on over the course of a decade, and the relatively benign beginnings of the mission obscure a tumultuous early period that did not escape the harsh realities of Spanish encroachment into Native lands. Bernard L. Fontana’s history of the mission, San Xavier del Bac: Portrait of a Desert Church, which served as a major resource for this story, notes a rising tide of unrest among the O’odham as diseases brought by the Europeans ravaged the Natives and the expanding Spanish presence grew more oppressive.

In 1734, a group of O’odham broke into the priest’s house at Bac and ransacked it, damaging or destroying vestments, altar cloths, and other symbols of Christianity. In 1751, the Pima Uprising, a revolt across the region, caused the Jesuits at San Xavier to flee until the Spanish regained control. The uprising had been spurred in part by callous treatment from many of the area’s missionaries, whose labor requirements of the O’odham (believed to have been paid in meals and, in some cases, wages) disrupted the community’s centuries-old agricultural practices. The missionaries also tried to prohibit traditional ceremonies. In specific incidents, Jesuit priests in nearby missions belittled and/or physically mistreated O’odham leaders, helping to spark a violent response that spread quickly.

Five years after the Pima Uprising, Friar Alonso Espinosa’s attempt to force the O’odham at San Xavier to abandon their traditional practices—including age-old religious rituals, dances, and festivals—led to another sacking of the friar’s residence. In one of those incongruous moments history sometimes provides, the leader of the military expedition sent to punish the O’odham paused on his way back to lay the cornerstone for an early church at San Xavier, a flat-roofed, unadorned, mud adobe structure that took five years to complete under Espinosa’s direction—with the O’odham, of course, doing most of the work.

The church, finished around 1761, served the small Christian community gathered around the mission until work began on something much grander. By then, the Jesuits were gone, recalled by the Spanish crown for political reasons, and replaced by Franciscans.

By the mid-1800s, the mission largely had been abandoned by the church, with circuit-riding priests visiting only rarely. Lieutenant Couts found it empty but kept by the O’odham “with incredible care.” In 1854, the United States acquired what is now Southern Arizona from Mexico through the Gadsden Purchase, leading the Mexican priests to formally withdraw. Four years later, a visitor traveling west found the mission’s abandonment complete. “The birds are its only occupants and they sing praises from morning until night,” traveler Phocian R. Way wrote in his diary in 1858. “They build their nests on the heads of the saints and warble their notes of joy while perched on their fingers.”

Others who came upon the mission at this time were less poetic, noting the roof leaked and plaster was falling in chunks. They predicted that within a few years the church would fall into total ruin.

The walls of San Xavier are built of burnt adobe bricks made of local clay and fired in kilns where the church’s rear courtyard now sits. The bricks form a shell filled with basalt rock hauled down from hills still visible in the distance. “It’s really a stone building with a brick veneer,” says Vint.

We talked as workers raised scaffolding up the sides of the 64-foot-tall east tower. The current conservation effort is focused on undoing earlier tower repairs that used cement plaster for resurfacing. This was once a common practice, but preservationists now know that cement prevents burnt adobe brick from breathing, trapping moisture and leading to its eventual deterioration. The project, which will cost about $1 million, is expected to be finished next spring. “Essentially, it’s removal of the concrete to the underlying burnt adobe, scraping off the concrete,” Vint explains. “It’s a matter of removing incompatible materials, adding compatible materials, and then adding a lime plaster.”

Lewis points out the varying sophistication of the artwork, which indicates that both accomplished artisans and apprentices put their brushes to San Xavier—another possible example of the two cultures working together. To pass on their conservation skills locally, Lewis and Rubio have taken on their own apprentice, Susie Moreno, a member of the Tohono O’odham Nation from San Xavier District who is studying sustainable building and heritage conservation at the University of Arizona in Tucson.

San Xavier continues to be integral to the O’odham people, particularly the Catholic faithful, with regular services, a mission school, and annual festivals and celebrations. “In general, most of the people from San Xavier, they’ve all been baptized here,” says Lewis, “had their weddings here, had their funerals here.”

The mission, designated a National Historic Landmark in 1960, also has long served as a source of regional pride. “Ever since Tucson’s Anglo business community began promoting it, the romance of the mission has been part of our psyche,” says Vint. “Very early brochures trying to convince people to come to Tucson often featured San Xavier. I was in Cub Scouts, and our Cub Scout troop built a scale model of the San Xavier mission out of little adobe bricks [we made using ice-cube trays]. We exhibited it at the Pima County Fair.”

The Catholic diocese made badly needed repairs to the dome and other parts of the structure early in the 1900s under Bishop Henry Granjon, whose dedication to the mission reportedly led him to pick up a trowel when needed and to reach into his own pocket when money ran dry. But other financial needs have pressed upon the church, and the cost of conservation and maintenance had clearly become too much by the 1970s, when a group of leading Tucson citizens formed Patronato San Xavier to save what they recognized as both a local and national treasure.

Since 1978, the Patronato has taken on the responsibility for preservation, relieving the parish and the Franciscan order of the burden. “Before Patronato stepped in, the building truly was at risk,” says Green. Roughly $14 million has been spent over the past 32 years for interior and exterior restoration and conservation, Vint says. Money has come from local supporters, the Getty Foundation, and the National Fund for Sacred Places, as well as a federal economic development grant.