“The Peruvian government is threatening to sue Yale University for the return of all the artifacts found at Machu Picchu. There’s no dispute that Peru gave Bingham permission to take the artifacts to Yale for further study. But Peruvian authorities say they have documents specifying that the material had to be returned within 18 months. It has now been more than 90 years. Yale says that Peruvian law in the 1900s “gave Yale title to the artifacts at the time of their excavation and ever since.”