San Sebastián is a small colonial church on a quiet plaza of the same name, about ten minutes' walk north of the central plaza. Built in 1581 to serve indigenous parishioners (the central churches were originally for Spaniards only), it preserves a striking patron-saint image of San Sebastián pierced by arrows and an unusual painted wooden ceiling in the side chapel.
The square outside is one of the most peaceful spots in the historic centre — palms, a small fountain, a few benches, and very little traffic. It is a useful detour on the walk between Parque Bolívar and the cemetery, and a quiet place to rest before tackling the next museum.