Route
Lima (sea level) ──── flight, ~1 h 30 ──── Cusco (3,400 m)
│
Sacred Valley (~2,800 m) ─ Ollantaytambo ─ train ─ Aguas Calientes ─ Machu Picchu
Machu Picchu is the obvious reason to add Peru's highlands to a Lima marathon, and the flight makes it easy. Cusco sits at about 3,400 m, so the sensible route avoids sleeping there on arrival. Instead, drive down from the airport into the Sacred Valley, which lies at roughly 2,800 m, and spend the first two nights there. That brings your body up in two steps and cuts the risk of altitude sickness.
Book flights, the train and the Machu Picchu ticket together. Machu Picchu has timed-entry tickets that sell out well in advance, and the train to Aguas Calientes, the town at the foot of the site, runs from Ollantaytambo on a limited timetable. Book the tickets before you book the rest. Do not book a same-week international flight home from Cusco, and check the current ticket rules and flight schedules before committing.
May in the Andes
May is the start of the dry season. Days are bright and warm in the sun, around 18 to 20 °C in Cusco, with clear skies and little rain. Nights drop to near freezing in Cusco and are milder in the valley. Pack layers, a warm hat and sun protection. The thin air makes the sun fierce.
Nights one and two: the Sacred Valley
Take a transfer from Cusco airport down to the valley, which takes about an hour and a half. Stay in or near Urubamba or Ollantaytambo. The streets of Ollantaytambo are a grid of Inca stone channels and cobbled lanes, where the recovery walk is the flat main street and the plaza. The Inca fortress above town has steep stone terraces and a climb of about 200 steps. Save it for the second day, when the legs have started to recover.
Rest on the first day. Drink water, avoid alcohol, and eat lightly. Many valley hotels have gardens and quiet courtyards.
Night three: Aguas Calientes
Take the morning train from Ollantaytambo to Aguas Calientes, a ride of about an hour and a half along a river gorge, with large windows on the roof. Spend the afternoon in the town, which is built along the river and the railway line. The streets are steep in places, and the town is busy with visitors.
Visit Machu Picchu the next morning by shuttle bus from town, on a timed ticket. Buses run up a switchback road in about 25 minutes. Once inside, the guided circuits are mostly on terraces and stone steps. Stairs are the hard part, and descents hurt after a marathon. Walk slowly and use the handrails where they exist.
Night four: Cusco
Return by train and road to Cusco for the final night. The city is at 3,400 m, so go slowly. Its centre is compact and cobbled, with the Plaza de Armas, the cathedral and the Qorikancha, an Inca temple with a colonial church built on top. The Hotel Monasterio, a Belmond hotel in a former seminary, and the Casa Andina Premium Cusco are two central choices. Avoid heavy meals and alcohol on the first night in the city. Coca tea is widely offered, and many visitors find it helps.
Getting home
Fly from Cusco back to Lima (LIM), then connect to your onward flight. Leave a full night in Lima before an international departure, because Andean weather and fog can delay flights. Check the train timetable and the Machu Picchu ticket rules before you book.