Santa Ana church, with its wooden altar and reed roof, is more rustic than others on the mission circuit and recalls the first churches constructed by the Jesuit missionaries upon their arrival. The interior contains exquisite religious carvings and paintings. Of particular interest is the church organ, which dates from 1754; the pipes have been replaced but the wooden exterior is original.

　　During recent renovations a diatonic harp, more than 1.5m tall, was also discovered; it’s displayed in the church.