This reconstructed pre-Columbian fortification is 1km south of the center across an iron bridge. Its situation is strategic, commanding the river valley both ways and, though the site was undoubtedly used earlier, the ruins date from the 11th to 15th centuries. There are great views and, seemingly, a cardón cactus for every soul that lived and died here. For further succulent stimulation, there’s a botanic garden by the entrance.
The 1950s reconstruction has taken liberties; worse yet is the earlier, ridiculous monument to pioneering archaeologists bang where the plaza would have been. Nevertheless, you can get a feel of what would have been a sizable fortified community. Most interesting is the ‘church,’ a building with a short paved walkway to an altar; note the niche in the wall alongside.