Peru Rail. Trains depart from Ollantaytambo, 1hr 45min from Cuzco, several departures daily, varying greatly in price. To get to Ollantaytambo, take a collectivo from Calle Pavitos in Cuzco, 15 soles per person. They start early, around 3am, and run every half hour. Look for a newish van with seatbelts. Ollantaytambo is a lovely town with some ruins of its own, so it is a good idea to take the bus, spend a night in Ollantaytambo, then take the train to Aguas Calientes the next morning. The scenic train journey through the Sacred Valley takes about 1 hour 45 as well. Tickets should be bought in advance either online or at the Peru Rail office on the Plaze de Armas in Cuzco. Try to book several days in advance if possible, especially in the high season. It´s not possible to select your own seats online, so if you have a preference, buy them at the station. The fares start at US$35 one way in the 'Backpackers' cars, with decently comfortable seats and small snacks provided. The 'Vistadome' cars are the mid-range cars, with more comfy chairs and meals served. If you prefer to ride in style, opt for the 'Hiram Bingham', complete with gourmet meals and an observation carriage. Some people consider this service to be obnoxious, given the poverty of the people it rolls past.
Inca Rail and Machu Picchu Rail run alternative services; their offices are also on the Plaza de Armas in Cuzco. Prices are service are similar; they are good alternatives if your chosen service on Peru Rail is fully booked.
By foot
If you're on a budget, or just adventurous, it's possible to hike downstream along the railway tracks from Ollantaytambo or from the town at km 82, where the Inca trail starts, this is about a seven hour hike (Note - hiking on the train tracks is prohibited).
It's also possible to hike upstream along the train tracks from Santa Teresa (4 hours) or Hydroelectrica (2 hours). You can take a minibus directly to
