Granted, it's no Monte Albán, but this pre-Hispanic site 600m north of La Bocana village is your only true glimpse of history in made-in-the-1980s Huatulco. Excavations are ongoing, but, to date, a ball court and two fairly modest temples have been uncovered. Adding to the appeal is a small museum, a jungle path to a spectacular clifftop lookout (site of an ancient 'guiding stone' possibly also used for sacrifices) and some new explanatory signs in Spanish and English.
The site was occupied by different groups between about 500 BC and AD 500, and again from 1000 to the 16th century. You can wander around on your own or hire a guide (M$480 for up to four people).
Parking costs M$10. A taxi to Crucecita is M$1000.