In 1971, Soviet geologists working in Turkmenistan set a crater on fire to prevent the spread of methane gas, expecting it would burn for a few days.
The hole has since been burning for over 52 years and is know as The Door to Hell.
https://video.nostr.build/eb1a1ee93a00982fc39656b5b252a6ce7758ddc7e44537ea0c479730ae3df203.mp4