The ancient Aztec civilisation has captured the imagination and intrigue of millions of people across the world. At one point, they were among the most advanced humans on the planet, leading the way in both fields of science and medicine.

They built great cities for hundreds of thousands of people, creating complex irrigation systems not seen for hundreds of years. But, in the early 16th century, after Spanish invaders reached Central American shores, the once-great civilisation fell to its knees and was lost forever.

The ancient city of Teotihuacan has since been excavated and studied by archaeologists, many travelling from the US and around the world to learn about how the Aztecs once lived and ruled.

One surprising discovery made beneath the largest pyramid in the city, the Pyramid of the Sun, was explored during Discovery’s short documentary, ‘Shocking Artefacts And Human Remain Found In 2000-Year-Old Pyramid’.

Here, archaeologists unearthed a tunnel in the bedrock, at first believing that it was a natural cave. However, on further investigation, they hit a carved out chamber, and beyond it, the remnants of 17 thick man-made walls, built to block access to the tunnel.

At the very end of the tunnel, they fund an elaborate chamber carved in the shape of a clover. Now, the tunnel lies empty, likely stripped of its contents by robbers over the centuries.

But, the discovery under the Sun pyramid was just the beginning: in 2003, a tunnel was discovered beneath the Feathered Serpent pyramid. Then, in 2017, Mexican archaeologist Sergio Gómez uncovered another secret tunnel under the Feathered Serpent pyramid.