If you don't fancy the four day hike, at least consider walking up to the Sun Gate, which takes about an hour - it affords a panoramic view of Machu Picchu and photo opportunities which make the effort worthwhile. This is the vantage point from which the classic Machu Picchu photograph in the guidebooks was taken. Make sure you cover as much of the site as you can in the time you have available - it's worth skipping lunch if you are only there for a few hours. We mentioned earlier the ecological significance of this region. Just a few statistics.
Wildlife is here in abundance.
And there are at least 170 species of orchids, mainly in the cloud forest. With only a third of the territory yet studied, there will obviously be further discoveries of new species. Part of Machu Picchu's romantic appeal is that it is shrouded in mystery. As with all Inca sites, the lack of a written language has led to many theories being propounded with little or no evidence to support them, some of them being subsequently disproved as scientific methods improve. For example, more than 100 sets of human skeletal remains were found in over 50 burial sites at Machu Picchu.