The world-famous archaeological site was the scene of a shooting this week when an armed man opened fire on tourists.
Traces of the ancient South American city can still be found in the roads and structures of modern Mexico.
Archaeologists have discovered a tunnel and chamber hidden beneath the 2,000-year-old Pyramid of the Moon.
Archaeologists have discovered a mysterious tunnel underneath the ancient city's Pyramid of the Moon.
Significant quantities of the metal have been found inside the Pyramid of the Feathered Serpent.
Archaeologists excavating a subterranean tunnel below the ancient city have unearthed three new chambers.