Puente del Inca

The Puente del Inca is a natural stone bridge formed by mineral-rich thermal springs over thousands of years — the yellow and orange sulphur deposits encrust the arch and everything around it, including the ruins of a 1925 spa hotel that the springs have been slowly incorporating into the mineral formation since an avalanche destroyed it in 1965. It spans the Río Las Cuevas at 2,720 metres in Mendoza Province, 177 kilometres from the city, at a point where the Andes proper begin and the road to the Chilean border climbs toward the Aconcagua massif. The hotel ruins and the natural arch are becoming the same object.

Puente del Inca is a natural travertine arch spanning 47 metres across the Río Las Cuevas, formed by the precipitation of calcium carbonate and sulphur compounds from the thermal springs that emerge from the surrounding rock faces. The springs reach temperatures of 38-42°C at source and are rich in sulphur, calcium, and iron, producing the orange and yellow mineral staining that covers both the arch and the spa hotel ruins abandoned after the 1965 landslide. The bridge is considered one of the seven natural wonders of Argentina and was the subject of an independence-era controversy — early-nineteenth-century Argentine authorities debated whether to tax the Inca highway crossing that the natural bridge serviced. The Aconcagua massif is visible 20 kilometres north from the bridge, and the road through Puente del Inca is the main approach route for expeditions to the Horcones Valley base camp.