Spanish Catholic Missions and Missionaries in Mexico and American Southwest
intended to spread Christianity to "heathens" in order to "civilize" them
usually with a central church building named after a particular Catholic saint, often built of heavy adobe (for insulation from the heat and for stability, but also because easier and faster to build than with quarried stone)
often with one or more bell towers or arched bell-screens (q.v. Pohl pp.28-29, 33-35)
often also contained smaller living quarters for priests and bishop, storehouses, schoolrooms, as outlying buildings of the same or lesser construction
In areas north of Mexico, arranged previously nomadic indigenous cultures into fixed pueblos (towns)