Peru week begins on an Inca ruler's mountain estate: the farmers living there when Hiram Bingham arrived in 1911, what the bones and DNA say about who served there, the water system that ran past the ruler's door, and why it was never really lost.
Machu Picchu stands in the Andes of Peru, northwest of Cusco, on a steep ridge more than 2,400 metres above sea level, with the Urubamba river far below. Here the high Andes begin to fall away toward the Amazon basin, and nearly two metres of rain fall in a year. About two hundred granite structures stand on the ridge. Even the biggest walls are fitted without mortar. The town has two parts, one for farming and one where people lived.
It was built in the fifteenth century as a royal estate for Pachacuti, the Inca ruler who did most to turn the Inca state into an empire. Spanish accounts say he took power in 1438, so scholars long assumed the estate went up around 1450. It was a country retreat for the Inca elite, run day to day by a few hundred servants and craftsmen. Around the Spanish conquest, in the sixteenth century, it was abandoned. Forest grew back over the buildings.
The farmers, the visitor and the bones
By 1911 two farming families lived on the ridge, growing crops on the Inca terraces. On 24 July that year Hiram Bingham, a Yale lecturer looking for Inca ruins, came down the Urubamba valley. A local farmer, Melchor Arteaga, told him of ruins on a mountain called Machu Picchu and went along as guide. They crossed the river on a rough log bridge and climbed for about two hours in a drizzle. At the farmers' hut a small boy was sent to show the way, and on the ridge Bingham found about a hundred terraces and houses of fine Inca stonework, overgrown by the forest.
In 1912 he returned with a larger team, backed by Yale and the National Geographic Society. They cleared the vegetation, searched the burial caves around the ridge and removed the remains of well over a hundred people. The team's bone specialist, George Eaton, judged that about four in five were women, which suited Bingham's idea that the place had housed the Virgins of the Sun, a community of chosen women.
When John Verano re-examined the collection, he counted 177 individuals and found men and women much closer to even; Eaton, it seems, had read small or broken bones as female. There were children among the dead, and few skeletons showed heavy labour. These were the estate's servants and caretakers, and some of their skulls had been deliberately shaped in childhood, in more than one style, a hint of mixed origins.
In 2021 a team led by the Yale archaeologist Richard Burger dated bones and teeth from 26 people with a refined radiocarbon method that needs only tiny samples. The estate was in use by about 1420 and until about 1530, some two decades earlier than the Spanish-based dates suggest. In 2023 the same project analysed ancient DNA from 34 people. Servants like these, called yanacona, were brought from conquered lands to serve the royal family, and their ancestry ran from the Pacific coast to the Amazon; about a third had significant Amazonian ancestry. Many had mixed ancestry, suggesting partners from other groups, and people of different backgrounds were buried side by side.
Following the water
The hydraulic engineer Kenneth Wright and his team traced the estate's water from a spring on the north slope of Machu Picchu mountain. There the Inca set a permeable stone wall into the hillside, with a trench behind it to gather the seepage. A stone-lined canal, roughly 12 centimetres wide and about as deep, carries it about three quarters of a kilometre at an average slope of about three percent. By Wright's calculations it brought enough water for about a thousand people.
The first fountain stands at the entrance to the ruler's residence, giving him first use. Fifteen more follow down the slope, linked by stone channels, each spout shaping a jet sized to fill an aryballo, the Andean clay water jug. The last could be reached only from the Temple of the Condor. For the rain, the town's walls hold about 130 drainage holes, and the terraces act as drains, with sandier soil and gravel under the topsoil. Wright estimates that as much as sixty percent of the building effort went underground.
Why it is listed, and the lost-city myth
UNESCO calls Machu Picchu probably the most remarkable urban creation of the Inca Empire at its height: a masterpiece of Inca art, architecture and engineering fitted to its mountain, and a unique witness to how the Inca organised their society. It also cites the mountain landscape, the long harmony between people and nature there, and the globally significant variety of life where the Andes meet the Amazon basin. It was inscribed in 1983, for both culture and nature.
It is often called the lost city of the Incas. Bingham had come looking for Vilcabamba, the jungle refuge where Inca rulers held out against the Spanish, and became convinced Machu Picchu was it. He was wrong. Scholars now place Vilcabamba at Espíritu Pampa, identified by the American explorer Gene Savoy in the 1960s. The ridge was never lost to the people who lived around it; in UNESCO's words, in 1911 it became known to the outside world.
Our week in Peru begins on a mountain ridge where nearly two metres of rain fall in a year. An Inca ruler built a royal estate up there, and one engineer estimates that as much as sixty percent of the building work is underground.
This is Ours to Keep. I'm Mira, and today: Machu Picchu. I'm an AI voice; the facts come from official records and checked sources.
The emperor's estate
Machu Picchu stands in the Andes of Peru, northwest of the city of Cusco, on a steep ridge more than 2,400 metres above sea level. Far below runs the Urubamba river. This is where the high Andes begin to fall away toward the Amazon basin. On the ridge stand about two hundred stone structures, built of granite. In the finest walls, such as those of the building called the Temple of the Sun, the blocks are cut and fitted precisely. Even the biggest walls use no mortar. Terraces climb the slopes around the town. The town is laid out in two clear parts, one for farming and one where people lived.
It was built in the fifteenth century as a royal estate for the Inca ruler Pachacuti. He was the ruler who did most to turn the Inca state into an empire. Spanish accounts written after the conquest say he took power in 1438. Scholars long assumed the estate went up after that, around 1450. It served as a country retreat, a place where the Inca elite could get away from the city. Its everyday population was a few hundred servants and craftsmen, and they kept the estate running.
The farmers and the bones
Around the time of the Spanish conquest, in the sixteenth century, the estate was abandoned. There is no sign the Spanish ever reached it. Over the centuries that followed, forest grew back over the empty buildings. By the early twentieth century, two farming families were living on the ridge, and they were growing crops on the old Inca terraces.
On the twenty-fourth of July 1911, Hiram Bingham, a lecturer from Yale, came down the Urubamba valley looking for Inca ruins. A local farmer, Melchor Arteaga, told him there were ruins on a mountain called Machu Picchu, and he went along as a guide. A Peruvian police sergeant named Carrasco came with them as an escort. They crossed the Urubamba on a rough bridge of logs. Then they climbed for about two hours in a drizzle. At the farmers' hut, a small boy was sent to show the visitor the way. Up on the ridge, Bingham found about a hundred terraces stepping down the slope, and houses of fine Inca stonework, overgrown by the forest.
Bingham came back in 1912 with a larger team, backed by Yale and the National Geographic Society. They cleared away the vegetation. They also searched the caves around the ridge, where the people of the estate had buried their dead. From those caves they took the remains of well over a hundred people. The team's bone specialist, George Eaton, judged that about four in five of them were women. That suited Bingham, who thought the place had housed the Virgins of the Sun, a community of chosen women.
What the bones say
Those bones have been studied again since. Later, John Verano went back over the collection and counted a hundred and seventy-seven people. He found the numbers of men and women much closer to even than Eaton had claimed. In his view, Eaton had read too many small or broken bones as female. Verano found children among the dead as well. Few of the skeletons showed the wear of heavy labour. These were people who served and cared for the estate. Their skulls already hinted at mixed origins. Some had been deliberately reshaped in childhood, and in more than one style.
In 2021, a team led by the Yale archaeologist Richard Burger dated bones and teeth from twenty-six of those people. They used a refined form of radiocarbon dating that needs only tiny samples. The results showed the estate in use by about 1420, and until about 1530. So people were living there around two decades earlier than the Spanish accounts suggest.
Two years later, the same project read ancient DNA from thirty-four people buried at Machu Picchu. The Inca called servants like these yanacona, people brought from conquered lands to serve the royal family. Their roots ran all the way from the Pacific coast to the Amazon. About a third of them carried strong Amazonian ancestry. Many had mixed ancestry, which suggests that people here chose partners from groups other than their own. And the dead were not sorted by origin. People of very different backgrounds were buried side by side.
Up close
Every one of those people needed water, so let's follow it, from the mountain to the ruler's door and on down the hill. The American hydraulic engineer Kenneth Wright and his team have studied this system closely. It starts at a spring on the north slope of Machu Picchu mountain, above the town. There, the Inca builders set a stone wall into the hillside, a wall that lets water seep through. A trench behind it gathers the water and feeds it into a channel. Measured in modern times, the spring gives from about twenty-five to more than a hundred litres a minute.
From there, a stone-lined canal runs about three quarters of a kilometre to the town. It is small, roughly twelve centimetres wide and about as deep. It falls gently, on average about three centimetres for every metre it runs, and gravity does the rest. The builders made it big enough to carry about twice the spring's usual peak flow, so it would not overflow. By Wright's calculations, it brought enough water for about a thousand people. The canal passes under the outer wall, across the farming sector, and under another wall into the town.
The first fountain stands at the entrance to the ruler's residence, so he had first use of the water. From there, fifteen more fountains follow one another down the slope, and stone channels carry the water from each one to the next. Each spout shapes the water into a jet sized to fill an aryballo, the clay water jug of the Andes. The last fountain could be reached only from inside a temple, the Temple of the Condor. Whatever water is left flows on into the town's main drain.
Then there is the rain, nearly two metres of it a year. The town's walls hold about a hundred and thirty drainage holes. The terraces hold the steep slopes against erosion, and they work as drains too. Under their topsoil lie layers of sandier soil and gravel, so rainwater filters down through them instead of pooling on top. Wright estimates that as much as sixty percent of the builders' effort went underground, into foundations and drainage.
Why it's on the list
So why is it on the list? UNESCO calls Machu Picchu probably the most remarkable urban creation of the Inca Empire at its height, and it gives four reasons. First, the town is a masterpiece of Inca art, town planning, architecture and engineering, fitted so closely to its mountain that it seems to grow out of it. Second, it is a unique witness to the Inca civilization. It shows how the Inca planned their use of space, and how they organised their society, their farming, their religion and their government.
The other two reasons are about nature. The record praises the landscape itself, its steep mountains and the long, balanced relationship between the people and the land around them. And it points to the living world. The sanctuary sits where the high Andes meet the Amazon basin, with many small climates and habitats, and many plants and animals found nowhere else. UNESCO counts its variety of life as important for the whole world. Machu Picchu was inscribed on the World Heritage List in 1983, for both its culture and its nature.
The surprise
Machu Picchu is often called the lost city of the Incas, and for Bingham that meant one place in particular. He had come to Peru looking for Vilcabamba, the jungle refuge where Inca rulers held out against the Spanish after the conquest. He became convinced that Machu Picchu was it. He was wrong. Scholars now place Vilcabamba at Espíritu Pampa, a site the American explorer Gene Savoy identified in the 1960s. Bingham had even been there himself. And the ridge was never lost to the people who lived around it. UNESCO's record says that in 1911 it became known to the outside world.
Tomorrow, from stone to grass: the Quechua communities who rebuild Q'eswachaka, a rope bridge over the Apurímac river, every year with Inca techniques.
