This question can be answered in a number of ways, such as
- Prypjat [1 in Ukraine (Chernobyl)
- Danakil Depression [2 in Ethiopia
- Crater of Derweze [3 in Turkmenistan
My vote goes to the Temples of Hell in Buddhist countries such as Thailand, Cambodia, Singapore, Sri Lanka, China, South Korea and others.
Attention: Some of the following pictures are quite crass.
As a kind of ghost train, the Buddhist temples of hell should not entertain but teach.
Surprisingly, children are taken to visit Hell’s Temples.
Visitors learn in a “Dantes Inferno in 3D” what happens when you violate the five virtue rules[4.
Often, the punishment has at least remotely to do with the act itself.
Buddhist hell is only temporary, not for eternity as in Christianity.
After being punished, you will be reborn normally and may try again as a worm in case of bad karma.
The temples are mostly off the beaten track.
But there are easily accessible exceptions such as Wat Mae Kaet Noi[5 near the tourist-popular city of Chiang Mai in northern Thailand.
Wat Saen Suk[6, right on Bang Saen Beach near Bangkok, is also within easy reach for travellers.
However, the morbid places are almost unknown outside the respective countries and you can only see locals there.
The pictures in the article are from the mentioned two temples.
There is probably a three-digit number of these temples in Thailand alone. Here is a list of Hell Temples in Thailand with many more pictures.