Puente del Inca

Puente del Inca is a natural travertine arch spanning the Río Las Cuevas at 2,719 metres on the road to the Chilean border — built by the springs themselves, calcium and sulphur precipitating layer over layer, staining the arch and everything near it orange and yellow. An avalanche took the thermal hotel beside it in 1965, and the springs have been mineralising its ruins ever since: architecture becoming geology in slow motion.

The arch runs some 47 metres, and the thermal water that made it still emerges warm and mineral-rich from the rock faces, continuously depositing new crust. The site is viewed from the marked perimeter — crossing the fragile bridge itself is prohibited, and the crusted hotel ruins are looked at, not entered, which is exactly what their strangeness deserves. The stop sits naturally on the high-Andes road: Aconcagua's massif stands visible to the north, the artisan stalls sell mineral-crusted curiosities made by leaving objects in the spring water, and in winter the yellow arch against snow looks even more improbable. Provisions come from Uspallata or Mendoza — the bridge itself offers little beyond a small shop and a large silence.