Santo Domingo is one of the old churches in Oaxaca. It has become something of a cultural, rather than a religious center, and there are museums and gardens. We have yet to go to the botanical garden in the back of the church, but the first three photos are from the front of the church at one of the side buildings. They were just planting these when we were here about 10 years ago and the botanical garden, which also features desert plants, was just under construction.
It seems impossible, but there are more churches in Oaxaca than there were in Merida and Merida is four times bigger.