The mysterious Underworld of Teotihuacan

What lies under the City of the Gods?

I have recently published an article on the Underworld of Teotihuacan on the Ancient Origins website. You can find the complete article here:

Ancient Origins - Descending into the Underworld of Teotihuacan - Labyrinthine Tunnels and rivers of Mercury

There are miles of natural caves and man-made tunnels under the ancient city in central Mexico, many of which remain to this day unexplored. Very much like in Egypt, there are rumors that also the pyramids of Teotihuacan are connected by means of underground passages, which may extend for a considerable distance under the valley of Mexico.

Early exploration reports describe vast chambers and pillared halls carved in the living rock, of which no indication survives in modern times. It is very well possible that some of the cave entrances to this underground labyrinth can still be found a short distance from the Pyramid of the Sun and the Pyramid of the Moon.

In february, our expedition team was able to document for the first time on video a small section of these tunnels, proving that not only do these tunnels form part of a vast network running under much of the present-day site of Teotihuacan, but that they are also unquestionably man-made.

More expeditions will be required to assess the true extent of this underground labyrinth, and whether these relatively superficial tunnels are just the tip of the iceberg of a much larger system of interconnected passageways and chambers.

Additional references: 
[1] Ancient Origins - The Rome of America - What lies under Teotihuacan?

[2] Uncharted Ruins - The Megalithic Ruins of Ancient Mexico: Teotihuacan