The Cordillera Blanca in Ancash carries more glaciated peaks above 5,500 m than anywhere else in the tropics, and the Huayhuash sits just south of it — shorter, sharper, emptier. Both work from Huaraz. They are roughly 800 km from Cusco and belong to a different trip, which is worth saying because the two are frequently marketed as one.
Around Cusco, the Sacred Valley sits lower than the city, which is why we sleep in it first. The Classic Inca Trail is 43 km over four days on original paving, crossing Warmiwañusca at 4,215 m. Colca is about 3,270 m deep at its deepest point and, more interestingly, terraced and continuously farmed since pre-Inca times, with Andean condors riding the morning thermals at Cruz del Cóndor. In the east, Manu drops from Andean cloud forest to 400 m lowland Amazon inside one protected block.
Country-level constraints that decide whether a date is possible.