Elder Scrolls IV: Oblivion - Shivering Isles

You don't need to be mad to quest here, but it helps

This ridge even runs through the capital city of the isles, New Sheoth, splitting it in two in true Berlin Wall-style. The stunning fountains and impressive waterfalls of Mania’s half of the city (known as Bliss) are a sight to behold, yet they drain into the half ruled by Dementia (known as The Crucible), and there the water congeals into dank, stagnant piles of sludge in the ass-end of the city. It’s a land split between Alice In Wonderland-style exuberance and the type of ancient and gloomy forests in which hobbits always seemed to be getting lost in the Lord Of The Rings movies.