The Pukará de Quitor is a pre-Columbian fortress city perched on a rocky outcrop above the San Pedro River, about 3 kilometres north of town. Built by the Atacameño people in the 12th century, it was a genuine defensive stronghold: the stone walls follow the natural contours of the cliff, making the position almost impregnable. The views down the river valley and across to the volcanoes on the horizon are outstanding.
The fortress consists of a series of walls, towers, and storage chambers spread across several levels of the hillside. The climb to the top is not difficult, but the path is rough underfoot and the altitude (around 2,700 metres) can slow you down. Most visitors take an hour or so to explore the whole site. A small site museum at the entrance explains the history of the Atacameño culture and their resistance to Inca and then Spanish domination.
The Pukará is reachable by bicycle from San Pedro (about 30 minutes on a flat road) or on foot in under an hour. Most tour operators include it on half-day Valle de la Luna excursions. Early morning or late afternoon visits avoid the worst of the heat.