In 1966 artists José Chávez Morado and Olga Costa converted a massive old well into their home and studio; before their deaths, they donated their home and its contents for public use. On display is a small, but fascinating, collection of items from the 16th to 18th centuries, including pre-Hispanic and modern ceramics, embroidery, furniture, masks and their own artworks. It's worth heading to the 'suburb' of Pastita to experience a side of Guanajuato you might otherwise miss.
The pretty approach follows the former aqueduct that ends at their house. Take any bus marked 'Pastita' from the eastern end of town.