When American explorer Hiram Bingham first laid eyes on Machu Picchu, he felt as if he had walked into a dream, writes Derek Cheng.
Shrouded in the morning fog, the empty paths and stone stairways of Machu Picchu lay before me, as empty as it has been for much of the last 500 years.
I walked alone along massive stone walls. The only form of life ahead of me was a solitary worker, whose presence had a ghostly feel as he ambled off in the distant mist.
For this privilege, I had risen at some unholy hour and climbed the 400m to beat the busloads to the front gates of the world's most famous ruins. I followed the designated tourist trail, past the famous agricultural terraces and the main plaza to the gates to Wayna Picchu, the razor sharp peak to the north.
The track is painfully steep and stabs every muscle in your body, as well as your lungs as they take in the mountain air. I all but collapsed at the top, 2600m above sea level, taking in the serenity of the clouded valley below.
When the fog lifted, revealing the beauty of Machu Picchu below, there were still only a dozen of us at the summit. Steep stone stairways spiralled down towards the ridge to the main part of the city. To the south beyond the urban sector, agricultural terraces clung to the slopes, while the pyramid of the observatory rose up from the western sector.
It seemed fitting that our first view of the ruins free from mist would be from such a vantage point, the site wrapped in a series of valley folds under the gaze of Mt Machu Picchu to the south. The sheer beauty was enough to forgive the monstrosity of the road zig-zagging up the eastern slope, bringing busloads of daily tourists.
The Incas would never have had such comfort. They walked for weeks over the Inca roads from Cusco, trickling over a mountain pass and through the sungate on the opposite ridge before descending into the city.
About 500 years ago, the city would have been abuzz with Inca royalty taking refuge from the colder climates of Cusco, which was the centre of an empire that stretched from modern-day Ecuador through Peru and Bolivia to central Chile and Argentina.
The site's permanent population was about 300, swelling to 1000 when the royal family arrived. And though the hundreds of terraces could only provide for about 55 people, an abundance of others along the valley more than made up the shortfall.
The ruins had been built by the first Inca emperor Pachacuti, whose reign lasted until 1471, but they were abandoned sometime between then and the Spanish conquest of the 1530s. Spanish accounts of the conquest make no record of the site, and it never suffered the defacing that they gave to other sites.
So it lay in the mountains, slowly enveloped by the jungle.
In the latter 19th century, explorers moved through the area and had a sniff of the site; in 1874 German engineer Herman Gohring published a map and an account mentioning Machu Picchu, and in 1876 French explorer Charles Weiner referred to the sites of Machu Picchu and Wayna Picchu, and that ruins were to be found there.
When American explorer Hiram Bingham arrived in Cusco in 1911, his second trip to the area, a new road had just been blasted from the city to the jungle. In his own account, Bingham says he had no suspicion of any ruins in the valley until he met local farmer Melchor Arteaga, who led him to the ridge.
"It seemed like an unbelievable dream ... the site held me spellbound," Bingham wrote of the discovery.
Nowadays the streets and plazas are bulging with thousands of daily visitors. But unlike the mist that hangs over the ruins everyday, some of the mystery surrounding the site will likely never clear.
That so little can be known for certain has lead to elaborate theories that simply cannot be disproved - such as the popular tale of a sacred site where the Virgins of the Sun were sacrificed to the Gods, their hearts ripped out and held up for swooping condors, claws at the ready.
This arose from the view, now discredited, that most of the bodies found in the cemeteries surrounding Machu Picchu were female. It was later established that the bodies found were male and female in roughly equal proportion, and that the crude way they had been buried - sacrifices would have been mummified - meant they were likely workers who had died on site.
Many archaeologists contend that the site was a winter retreat for the noble Inca classes, religious only in the sense that, during the winter, the Incas still conducted their usual ceremonies.
We descended Wayna Picchu down a path to the Temple of the Moon (one of several seemingly random titles), discovered in 1936 and consisting of stone structures inside overhanging caves.
At the entrance to one of the caves is a seat carved into a mammoth rock, an example of exquisite Inca masonry, and their practice of incorporating natural beauty where possible. They used hammerstones and bronze and silver tools to shape their rocks, and often fitted them without mud or any kind of mortar.
By the time we returned to the main plaza, the site was crawling with people. The place had certainly lost some of its mystique from the morning and, yearning again for solitude, I headed for Mt Machu Picchu.
After passing along several narrow tracks on the edge of sheer precipices below, I arrived breathless at the summit. Before me the Urubamba River crawled through a series of mountain ranges that stretch to eternity, as the skeletal remains of Machu Picchu radiated below the shark-tooth of Wayna Picchu.
The mountain I was standing on was the water source for the city. From the springs ran a canal 749m to the main site, carrying 300 litres a minute.
In the middle of the city, the canal leads to 16 cascading fountains over a vertical drop of 26m. The fountains each have a channel creating a jet of water into a stone basin.
As well as sophisticated water engineering, the Incas also had drainage methods to channel rain run-off from roofs, and used several channels and holes in the walls to drain rooms.
I retraced my steps back to the city and through the main gate to the royal residences, which would have been decorated with fine textiles.
"The Inca did not have our kind of furniture. They incorporated niches and pegs into the walls for storage," wrote Ruth Wright and Alfredo Zegarra, who were the site's resident archaeologists for many years, in their guidebook to the site.
"They built raised platforms on the floors and perhaps placed alpaca skins and blankets on top to make beds or places to sit.
"Their houses were plastered on the inside with either gypsum or fine clay in light colours."
To protect the site from the inevitability of landslides, hundreds of walls were erected to create flat spaces. Some 60 per cent of Machu Picchu lies underground, a labyrinth of foundation walls and drainage for the terraces and walls.
I walked through the unfinished temples of the Sacred Plaza, with their use of enormous, smooth stones, and climbed the steps to the Intiwatana, meaning "place to which the sun was tied".
But the name is misleading; Bingham christened the name, thinking the vertical part protruding from the base was a sundial. But Incas used the horizon, not sundials, for solar observation. The accepted view is that the stone is simply a homage to the surrounding mountains. As you approach the platform from the west, the stone aligns itself with Wayna Picchu in the background.
As the sun started to set, we could imagine the royals leisurely relaxing in their homes, priests attending the temples, servants gathering water and maize. An ordinary existence in an extraordinary location, one we can still appreciate thanks to the Spanish never finding it.
Getting there: Access to Machu Picchu is via the Inca Trail, which takes you directly through the sungate into the site, or through the nearby small town of Aguas Calientes, which can be accessed via taxi, train or on foot. From Aguas Calientes you can take a bus (US$8 one way, or $15.50 round-trip), or walk. Entry fee to Machu Picchu is 128 soles ($60).