Fly Lima to Cusco (about 90 minutes; book the morning arrival so day one is a full acclimation day, not a travel day). Cusco sits at 3,400 meters — higher than anywhere else on this trip — and the only job today is letting your body catch up. Walk slowly. Drink water constantly. Say yes to the coca tea every hotel offers; it's genuinely useful, not a tourist gimmick.
When you're ready for a gentle loop, start at the Plaza de Armas: the massive stone cathedral, the colonial arcades, the flower sellers on the steps. Then walk ten unhurried minutes to Qorikancha, the Inca Temple of the Sun, where the Spanish built their church directly on top of the finest Inca stonework in the city — the contrast is the whole story of Cusco in one building (~$8 entry).
Where to stay
Casa Cartagena (boutique, courtyard pool, oxygen-enriched rooms on request), Antigua Casona San Blas (colonial house, fireplaces, San Blas views), or Tierra Viva Cusco Centro (solid mid-range, two blocks from the plaza). All three sit in the historic center, so nothing today requires a taxi.
Book a hotel with oxygen-enriched rooms if you're altitude-anxious — several Cusco boutiques offer them, and the first night is when it matters most. Diamox (acetazolamide) helps too; talk to your doctor before you fly, not after you land.
Evening: wander the whitewashed lanes of San Blas, the artisans' quarter, as the light goes gold over the red tile roofs. Dinner at a courtyard restaurant — lomo saltado and a pisco sour each (one, not three; alcohol hits twice as hard at altitude). Then an early night. Altitude rewards the patient, and tomorrow you descend to air you can actually breathe.
