This is a large dark-gray castle hidden deep under the Atlantic ocean. It's very Gothic style palace that can be found underwater. The only way to it is by teleportation which all demons can do. Here is where the 'royals' stay. There isn't much of a government system, it's mainly a monarchy. This is where all demons are born.
Inside the halls are a startling white and every door is ten feet tall, the ceilings fifteen feet. Down the main hall there is a single set of double doors that leads to the 'throne room'. Here is where the royals spend most of their time. There is a set of rooms off to the side for where they live. The opposing side of the royal's living quarters is another set of halls which house the infirmary, extra rooms, and prisons. The rest of the many rooms are simply randomly assorted.