The San Xavier del Bac Mission is located just off of Interstate-19 at Exit 92, on the San Xavier Indian Reservation, 6 miles south of Interstate-10 in Tucson. It is one of the oldest and most well preserved missions in the southwest.
The present church was built from 1783 - 1797 by the Franciscan Fathers Juan Bautista Velderrain and Juan Bautista Llorenz. Little is know about the actual labor of the construction of the church, who was the architect, who were the artisans, but many believe it was the Tohono O'odham who fufilled these roles.
The church is a series of domes and arches that create enclaves for themes of painting on the various walls, domes and rooms. The area behind the high altar is a dazzling gilt of colors. The wall paintings are all original.
The east tower was never completed. Several theories exist about why it was left unfinished. It is not known if the church's 7,000 peso loan was not enough, or if the priests decided not to finish it so that no taxes would have to be paid. Another theory says that a worker was killed during construction and no one else could be convinced to go up.
The church is open 365 days a year and is a working catholic church.

