Archaeologists have discovered 'a recreation of the underworld' at the ancient city of Teotihuacan in Mexico thanks to a radar device.

Researchers have only advanced 7 metres along the tunnel but the radar has revealed it to be 120 metres long and covered in symbols. It is thought that the passage leads to three chambers and may help explain the beliefs of the civilisation.

The tunnel, which is 13 metres below the ground, was originally discovered by chance in 2003 after heavy rains seeped into a tiny hole in the ground. No monarch's tomb has ever been found at the site near Mexico City.

Sergio Gomez Chavez, an archaeologist at Mexico's National Institute of Anthropology and History, said: 'At the end, there are several chambers which could hold the remains of the rulers of that Mesoamerican civilization.

'If confirmed, it will be one of the most important archaeological discoveries of the 21st century on a global scale.'

'We know that Teotihuacan was built as a replica of how they saw the cosmos, the universe. We imagine the tunnel to be a recreation of the underworld.'

Teotihuacan, with its huge pyramids of the sun and moon, is made up of a labyrinth of palaces, temples, homes, workshops, markets and avenues.

The city is thought to have been built in 100BC and existed until the 8th century. Archaeologists consider it one of the most influential in pre-Hispanic North America, with a population of 200,000 at its peak.

Only 5 per cent of Teotihuacan has been excavated despite more than 100 years of exploration. Read More