The longest day of the trek is 17km and starts with a short climb where the Incan ruin of Runcu Raccay is located. It is believed to have been constructed as a rest place for travellers and has a direct view to two other Incan constructions so may also have been used for communication. Another extended uphill section passes two lakes, where a deer is sipping water.

The top of the second pass marks the 'pretty much all downhill from here' point. I scramble up a hill off the trail where those who have any energy left can leave a rock to mark their visit. It provides a 360 degree panorama of the surrounding Andes. The long steep decline begins with a stop at Sayac Marca which has a dramatic setting on the hill side. It was used as an Incan fortress to guard the valley below, and it certainly has a good spot to see everything going on.

The trail clings to the mountainside as it descends into the highlands of the Amazon rainforest where hummingbirds speed between the tropical flowers. The trail is much quieter now since groups spread out much more in the faster sections.

It is a very enjoyable walk through the forest as the steep steps shallow out and the scenery turns more "Machu Picchu like". The path is often wet from the dribbles of water deposited by clouds which rested here early in the morning. After the third and final pass through the mountains the path descends very steeply. Here we get the first view of Machu Picchu mountain, on which the archaeological site rests on the other side. The mountain home of one of the Seven Wonders of the World is described as "the bigger of the two small ones over there."

I get the feeling that the Incans who built the trail in the 1300s had smaller feet than I do. The steps are narrow, though the porters literally run down, seemingly taking a leap of faith with each step. The path descends through an impressive 20m section of path cut into a cave before the ruins of Phuyu Pata Marca. It was clearly an important site for the Incas since the stonework is fine and the rocks interlock perfectly like a jigsaw. It is believed to have been used as a temple to the water god. A very impressive set of terraces are visible from across the valley. The trail later leads through these before leading to the campsite.

The campsite is very odd indeed. With a beautiful view over the Sanctuary of Machu Picchu Reserve, the tents are crammed around an ugly tin shack which blasts Greatest Hits 1999 around the site. I'm not sure that anyone appreciates the racket so I'm not exactly sure why they play it. Buying a bar of Snickers involves tighter security than you would expect at most banks. My tent certainly has an excellent view, just have to be careful of the cliff edge which sits six inches from the front flap.

The porters knock up a giant final meal and there is at least four times too much food. They introduce themselves at the overly formal ceremony of the tip. It turns out that one of them is 57, and he does this week in, week out. Certainly very impressive going.