Work on the Tucson landmark—commonly referred to as a cathedral, even then—was completed by 1868.
It was only in 1928 that the brick structure was transformed into its present Mexican baroque form, including the cast stone façade, which was inspired by the Cathedral of Querétaro, Mexico.
As part of the first ground-up restoration project since 1968, the oldest cathedral in town began renovations under the leadership of John Alan a Phoenix artist and Historic Preservationist. The artist recognized the existing and potential beauty of the church and was brought in to enhance the sacred space and worship experience. Trompe l'oeil (meaning "fools the eye") style painting and ornamental art are used frequently to create a more inviting atmosphere within the church.
The cathedral's floor is set on a slight grade, so that the main altar is clearly in view of the entire congregation. The seating can accommodate up to 1,250 people.
The side altars, also known as retablos, were made from handcrafted wood.
and, I believe, this one is decorated to honor the Blessed Sacrament Chapel.