You can take a bus from the non-descript Angels Inn to Monte Alban, the pyramidal residence of the area's native ancestors, for around $15 US dollars.

At Monte Alban, you can take guided tours in English or walk around the ruins yourself. Allow at least an hour or two to cover the grounds and the museum onsite built to house the artifacts collected. There is a small cafe that serves drinks and refreshments if you need a rest. Be sure to bring sunscreen and hats to protect yourself from the sun as it can get very hot outside.