At the Hidroelectrica train station. You can reach Machu Picchu only via train or on foot. On my way to Machu Picchu Village (Aguas Calientes) I walked from Hidroelectrica along the railroad tracks. On my way back I took the train. I had a first class ticket, but didn't even know about that. I didn't notice that I entered the wrong compartment. We already started when I figured it out. After about half of the journey the train had to make a stop and a train attendant ran with me to my compartment. There I was completely alone except for two other passengers and the service staff.😁