The Cusco - Machu Picchu Express
The only way to Machu Picchu is by walking (Inca Trail - which takes at least 4 days) or by train, which has a route almost as spectacular as the trail - but takes "only" 3 1/2 hours. Last year parts of the track was destroyed by the wild river next to it and Machu Picchu was isolated from the rest of the world for 66 days...
It is a truly scenic trip, especially with the special "Vista Dome" train, which has a sort of glass ceiling. No wonder this counts as one of the best train journeys of the world. We enjoyed every minute of it.