Why Machu Picchu is special
Most travelers agree that Machu Picchu in Peru is the world's most dramatic ruins. Machu Picchu sits boldly perched on a steep sided mountain saddle far above the partially encircling Urubamba River gorge.
What remains of the precision stonework of the pre-Colombian Inca temples and palaces clearly reveals how exalted Machu Picchu was in its glory days.

The Lost City of the Incas
Just before the Spanish conquest, Machu Picchu was mysteriously abandoned - and this was when it was still in its golden age. Machu Picchu subsequently lay buried under dense mountainous vegetation until 1911 when Yale explorer Hiram Bingham discovered it and began the reclamation process.

Experts debate Machu Picchu's purpose
Archaeologists disagree on whether Machu Picchu was primarily a citadel, religious site or royal retreat.
For decades the prevailing beliefs have been that Machu Picchu was principally either an Inca military stronghold or a religious center - or a combination of both.
Although there is scant evidence that Machu Picchu was an important sacred site, the stronghold theory bears weight because the builders chose an enviable defensive setting bordered on three sides by precipitous river canyon walls. Moreover, the Machu Picchu inhabitants could survive a long siege. They were self-sufficient regarding food because they farmed and ranched the verdant Machu Picchu terraces.
Still, the Machu Picchu citadel theory has a weakness. Would there be sufficient military value to justify constructing a major citadel in Machu Picchu's remote location?
Recently two archaeologists threw a monkey wrench into the Machu Picchu stronghold vs. sacred site dispute. Their research suggests that Machu Picchu was built mainly as a spectacular summer mountain palace. If so, the Machu Picchu planners knew what they were doing.

What leading travel books say about Machu Picchu
Machu Picchu is the most dramatic and enchanting of the Inca citadels.
Peru
Rough Guides

There is a tremendous feeling of awe on first witnessing Machu Picchu.
Peru
Footprints