At first glance, it could be a dramatic scene from a science-fiction movie.

But this giant hole of fire in the heart of the Karakum Desert is not the aftermath of an attack on Earth, launched from outer space.

It is a crater made by geologists more than 40 years ago, and the flames within have been burning ever since.

Welcome to Derweze in Turkmenistan - or, as the locals have called it, 'The Door to Hell'.