Three museums are sited in one impressively designed complex in the hills above Guanajuato. One collection explores the mining history of the region. The second has 36 mummies discovered in local churches (they look pretty gruesome so consider missing this one if you have children with you). The last looks at Day of the Dead celebrations and the Catrina dolls (an image/figurine of a skeleton in female clothing) that are a key part of the tradition.
To get here, take a 'Cristo Rey' bus, which depart every hour or so from near Alhóndiga (M$40 return).