The Karazhan Crypts was a dungeon that was cut from developers, but it was never removed from the game.
The abandoned level was, in the early days of WoW, still accessible through an in-game glitch. The easiest way to access the dungeon was die on one side of the door that walled of the level, and resurrect on the other side.
What players found was equal parts creepy and just down right fucked up.
As you made your way down hallways filled with decomposing corpses, you come across a flooded portion of the prison. As you dived beneath the surface, you get your first glimpse of them. Dozens of corpses chained to the ceiling. A dungeon full of prisoners sentenced to death by drowning with their hands and feet cut off. Yeah, we weren't prepared for that either. Take a look at the image above and imagine finding that in a supposedly walled off section of the game.
The dungeon was scrapped by developers because they were concerned that the dungeon would give them an M instead of a T rating. After The Burning Crusade expansion, Blizzard built an invisible wall around the door of the dungeon. The creepiest part? They never actually took it out. It's still just sitting there inside the game.