The chapel at the Parador-Museo Santa María is a religious art museum with an interesting array of colonial-era work from Europe and the Philippines as well as Mexico and Guatemala. The exhibits are well lit and displayed and feature lots of dark, brooding works focusing on the power of the church and God, and the nasty fate that awaits those who veer off the path of righteousness.
It's worth going in if you're here; otherwise, consider twice unless you're an aficionado of the genre.