In ancient times, animals would be led to Plutonium by priests as part of a sacrificial ritual, and the crowd would look on in awe as the beasts dropped dead once inside the temple's cave-like interior. This earned the building a reputation as a passage to the underworld. Today, birds and insects have been known to perish upon entering and scientists recently discovered the cause – a fissure deep beneath the structure that releases toxic levels of carbon dioxide.

Check out the remarkable discoveries unearthed by recent droughts

Incredible new secrets of the world's ancient wonders revealed