A Village Older Than the Incas
People have lived in this stretch of the Atacama since long before San Pedro had a name. At Aldea de Tulor, a few kilometres southwest of today's plaza, archaeologists have dated circular mud-and-vault houses to around 380 BCE — among the oldest confirmed human structures in the desert, built by the ancestors of the Atacameño people who still live here. A few centuries later those same communities raised Pukará de Quitor, a stone hilltop fortress above the San Pedro river, to watch the valley below. It held for generations until 1540, when a small force under Francisco de Aguirre broke its defenses during the Spanish conquest of the region — a defeat still marked at the site today.
The town's own name comes later, from the 1745 adobe church that still anchors the plaza: one of the oldest and most complete examples of Andean colonial religious architecture in northern Chile, its roof beams cut from cactus wood because no other timber grows within reach. Long before the Spanish arrived, though, this had already been a crossroads — a stop on trade routes linking the altiplano, the Pacific coast and the salt flats to the south, and later a resting point on cattle drives between Argentina and the nitrate ports of the coast.
The Driest Place That Still Has People In It
The Atacama is widely described as the driest non-polar desert on the planet, and parts of it have gone recorded decades without measurable rain. San Pedro survives inside that extreme because of the Río San Pedro and the network of underground water it feeds — the same water that let Tulor's builders farm quinoa and grow algarrobo trees two and a half thousand years ago, and that still irrigates the oasis belt of poplars and orchards around the modern town. Everywhere the water reaches, the desert turns green in a single line; a few steps past it, nothing grows at all.
That extremity has a second consequence that reaches well past agriculture: San Pedro's night sky is one of the clearest and darkest anywhere in the world, the same combination of altitude, aridity and near-zero light pollution that eventually drew the ALMA radio telescope array to the plateau above town — one of the largest astronomical observatories on Earth, built specifically because so little else could compete with these skies.
A Town the Lithium Boom Changed Twice
For most of the twentieth century San Pedro was a small agricultural and pastoral village, its economy built on the oasis's own crops and livestock rather than any outside industry. That began to shift in the 1980s and 1990s, first as Chile's mining industry expanded into the vast lithium brine deposits of the neighbouring Salar de Atacama — among the richest lithium reserves on the planet — and then, almost in parallel, as international travellers discovered the same landscape the miners had come for: the salt flats, the geyser fields, the high-altitude lagoons and the Valle de la Luna just outside town.
Tourism has since overtaken agriculture as the town's main livelihood, and the population has grown accordingly, but the built town itself has stayed close to its original scale — a grid of low adobe buildings a few blocks wide, still centred on the same plaza and the same 1745 church the Atacameño and Spanish left behind. What changed is what surrounds it: a ring of lodges, tour operators and restaurants serving a desert that, for two and a half thousand years, was mostly known only to the people who found a way to live in it.