The Forbidden Mountain is a mountain hidden 18 kilometers away from spawn. Not much has traveled in because no one dared to destroy the Forbidden Block which when destroyed exploded and broke apart the obsidian walls. If anyone dared to get in, that was only Notch and Herobrine. There is no way to get in in Creative other than destroying the Forbidden Block. As long as the mysterious block isn't destroyed, obsidian in the wall is regenerated. Herobrine resides in here and it is a very creepy, extremely wide and ultimately tall mountain. Hence, the obsidian walls are extremely very wide and ultimately very tall. On top is a haunted mansion, and in it, resides Herobrine and a lot of zombies and skeletons. Creepers live in the roof, and the only entrance to the roof insides is the chimney.