Cusco.

At 11,000 feet, Cusco makes you earn it — climbing stairs counts as cardio here. Sip the coca tea, befriend a llama, and let your lungs adjust before the Andes really start showing off.

Cusco was the capital of the Inca Empire, and it still feels like it — polished stone walls, Quechua spoken in the markets, and trailheads in every direction. Most travelers come for Machu Picchu, reached by the classic Inca Trail, the quieter Salkantay and Lares routes, or a comfortable train through the Sacred Valley. Add a sunrise trek to Rainbow Mountain, then catch your breath with river rafting, ziplining, or a 4x4 quad-bike spin past Andean villages.