Archaeologists have discovered a collection of thousands of mummies in a shanty town close to the Peruvian capital, Lima.
They date from the last years of the Inca civilisation, around 500 years ago.
The scientists describe the find as an unparalleled opportunity to learn more about Inca society.
So far, the archaeologists have retrieved about 2,200 mummies, though they believe there could be as many as 10,000 altogether.
Grouped burials
The mummified corpses come from every part of Inca society - rich and poor, young and old.
Some are still wearing head-dresses made of feathers which marked them out as high-ranking people.
Many were buried in family groups - parents, babies and elders, wrapped together in protective cloth, often alongside prized possessions.
Around 50,000 artefacts have also been discovered, including pottery, animal skins and food.
Unique insight
The scientists say the area was probably a major cemetery for the Incas between about 1480 and 1535.
The Inca civilisation ended in the 1530s with the arrival of the Spanish conquerors who then banned mummification which they saw as a pagan rite.
Mummification was practised in several parts of South America from as early as 7,000 years ago, but burial sites created by the Incas and other civilisations were destroyed by the Spaniards.
That means intact mummies are rare and a find on this scale, the archaeologists say, provides a unique opportunity to study the Inca society which once dominated the western regions of South America.