Ausangate is a 6,384-metre crown of glacier and rock southeast of Cusco, the highest mountain in that region of Peru, and the herders who live under it treat it as a guardian spirit. Its meltwater feeds the river that waters Cusco, so it is handled as a source rather than a landmark, and it still receives offerings. Those herders live above 4,000 metres with alpaca and llama, and their horsemen, the arrieros, run the pack animals on a circuit that rings the peak in four or five days over passes above 5,000 metres. They will take you out on horseback along the same tracks, which is a mercy at this height, where walking uphill is slow, thirsty work. The camps stand on the shores of glacial lakes that shift from emerald to pale blue as the light moves, and at some of them a hot spring thaws you out before bed.
Vinicunca, the Rainbow Mountain, is the day trip. A road from Cusco reaches a trailhead above 4,600 metres, and the walk climbs to a ridge at 5,200. What makes it hard is the height, not the distance: the walking is slow and you stop more often than the ground suggests. On the crest the bands are close enough for you to read one at a time. Iron oxides make the rust-reds and pinks, sulphur the yellows and copper the greens, and each band is a different ancient seabed or floodplain, stood on end when the Andes rose. Most walkers turn round at the viewpoint, and the crimson bowl of the Red Valley beyond it stays empty. In the weeks before Corpus Christi tens of thousands of pilgrims camp under a neighbouring glacier in the Sinakara valley for Qoyllur Rit'i, the star-snow festival, and dance for days in masks. The stripes themselves lay under ice until it melted off them around 2015. Nobody outside these valleys had heard of them a decade ago, and now a thousand people a day walk up a mountain that is still being prayed to.