In the hot, expansive Karakum desert in Turkmenistan, near the 350 person village of Derweze, is a hole 328 feet wide that has been on fire.
This hole is known as the Darvaza Gas Crater or the "Gates of Hells" by locals, the crater can be seen glowing for miles around.
The hole is the outcome not of nature but of an industrial accident. In 1971 a Soviet drilling rig accidentally punched into a massive underground natural gas cavern, causing the ground to collapse and the entire drilling rig to fall in. Having punctured a pocket of gas, poisonous fumes began leaking from the hole at an alarming rate. To head off a potential environmental catastrophe, the Soviets set the hole alight. The crater hasn't stopped burning since.
Turkmenistan plans to increase its production of natural gas. In April 2010, the President of Turkmenistan visited the site and ordered that the hole should be closed, or other measures be taken to limit its influence on the development of other natural gas fields in the area.
Though little information is available about the fate of the Soviet drilling rig, presumably it is still down there somewhere, on the other side of the "Gates of Hell."