A castle with spacial and/or sub-spacial distortions that allows one to activate the many Universes within it's limitless domain. The Omniversal Castle isn't always just a castle. In the "Hallway Of Infinite Doors" you can enter into any version of the castle that you want. Want an efficient robotic castle? Or a castle made of gold or candy? A door within the "Hallway Of Infinite Doors" will appear to give you just that! The rest of the castle (or the rest of any version of the castle) will always function with many other main doors. The way you know that they are the main doors is by their enormous sizes. By default, there are glass panels next to each main door around the castle, that presents a browsing mechanism of options to choose what kind of world you want to enter within the castle. Think about it like you're entering the Holodeck, except everything is real. The default time-zone at this castle will make it so time stands still in any other fictional universe. You can spend thousands of years here, and neither you, nor anybody you know in any other place/Universe will undergo the process of aging. The origin of this castle is physically impossible to describe, due to its Omniversal nature. However, there are often types of creatures that inhabit the castle, whose species are strongly random, and half of them can travel through all aspects of space, but not time, considering the fact that the castle is timeless. But considering this castle-world is literally timeless, I'm afraid I cannot give you a background story of this place. For all things have already happened an infinite number of times, and in an infinite number of different ways for each time.