Sajama is the highest mountain in Bolivia, a near-perfect snow cone of 6,542 metres standing alone on the altiplano near the Chilean border. It looks taller than it is because there is nothing beside it. The plain it rises from is already above 4,200 metres before you start, and the trees on the mountain's lower slopes are the highest woodland on Earth. Queñua grow up to 5,200 metres here. They survive it by wrapping themselves in thick, peeling, paper-like bark that traps air against the nightly frosts, and they gain a few centimetres a year, rarely passing five metres. They cluster wherever snowmelt or a spring reaches the surface, leaving bare ground in between. Llamas and alpacas drift between the stone-walled villages, and wild vicuña graze the tussock in the mountain's shadow.
Before sunrise the geothermal field west of the mountain seems to breathe. Jets of steam and pools of bubbling water burst from cracks across the plateau, loudest while the air is still cold, and in places the ground is thin and scalding under your boots. A short walk away are pools that sit at about 40°C, and you can lie in one with steam coming off the water and the white cone on the skyline. The villages keep their surprises indoors. Their churches are plain adobe outside and painted floor to ceiling within, biblical scenes over every surface. Out in the valleys stand chullpas, tall Aymara funerary towers of mud brick, some still carrying their painted geometric patterns. The mountain itself is a serious climb, glaciated and thin-aired, and it takes you two days with a guide. Most people stay on the plain, which is where the strangest thing here is anyway. Thousands of dead-straight lines are scratched across it, some running twenty kilometres over hills and gullies without a single bend. They were made by scraping the dark surface stones aside to show the pale soil underneath, and people kept adding to them for more than three thousand years — most likely paths between shrines, tombs and holy places.