We hiked the "short" Inca trail which takes 5-6 hours and is 12 kilometers long. The path is carved into the mountain with the first 2-3+ hours being a hike up the mountain side (somewhat gradual but lots of rocky stairs as well). Once you reach the beautiful ruins of Winay Wayna, the trail is fairly flat with a few up and downs until you have to climb up the stairs to the Sun Gate. After the Sun Gate it is all downhill to reach Machu Picchu. This was a difficult hike and we were exhausted by the end of it. All that to say it is worth preparing for and doing if you can. It was the highlight of our trip, despite the difficulty.