How well do you know Machu Picchu?
Built by the Inca high in the Andes, Machu Picchu still puzzles engineers. These six questions explore its name, stonework, hidden foundations and how it reached the world's attention.
Did you know?
- The carved stone known as the Intihuatana, often translated as 'hitching post of the sun', stands on a high point of the site. Researchers believe it was linked to Inca astronomy and ceremonies, with its angles and edges relating to the movement of the sun through the year.
- A 2021 study using radiocarbon dating of human remains found that Machu Picchu was occupied from around 1420, roughly two decades earlier than historians had estimated from Spanish colonial documents. It shows how scientific dating can refine what written sources suggest.
- Llamas graze freely on some of Machu Picchu's grassy terraces, helping keep the grass short. The surrounding sanctuary also shelters hundreds of species of birds and many kinds of orchids, which thrive in the cool, misty air of the cloud forest.
How the Inca built a city on a ridge
Machu Picchu sits on a ridge about 2,430 metres above sea level, high above the Urubamba River in southern Peru. It was built in the 15th century, most likely as a royal estate for the Inca ruler Pachacuti, and was home to a few hundred people, including servants and craftsmen. It was abandoned within about a century, around the time of the Spanish conquest, and the Spanish never recorded it, which helped its buildings survive. It became a UNESCO World Heritage Site in 1983.
Stonework without mortar
The Inca used different building styles for different purposes. Temples and royal buildings were made from finely cut granite blocks, shaped so precisely that a knife blade cannot slip between them. Ordinary houses and storerooms used rougher stones held with clay. Much of the granite came from the ridge itself, where a quarry area can still be seen. Workers shaped the stone with harder hammerstones, and walls often lean slightly inward, which, together with the trapezoidal openings, makes them more stable.
Water and terraces
The city's water came from a spring on the mountainside, carried by a stone channel to a series of 16 fountains, one after another down a staircase. Around the buildings, hundreds of terraces were cut into the slopes. They provided flat land for crops such as maize and potatoes, but they were just as important for engineering: layers of topsoil, sand and gravel let rain soak in and drain away safely, stopping landslides from carrying the city down the mountain.
Protecting the site
Machu Picchu receives large numbers of visitors, so Peru limits how many can enter each day and sells timed tickets for set routes through the ruins. Most people arrive by train to the town of Aguas Calientes, then take a bus up a winding road, while others hike the Inca Trail with licensed guides and permits. Climbing Huayna Picchu requires a separate ticket, and numbers are tightly controlled because the path is steep and narrow.