Remnant - an endless gray tower with no doors and no windows, hidden in Enuma Elish. The only way to find it is if you are given permission. The only entrance is for those permitted, willed into it.
Inside are memories of the old universe, stored and sealed away. The entire structure is, in fact, nothing but memories of the old world. The memories can be accessed by asking the tower.
Currently, the insides change to reflect what those who enter it expects to see, but the tower's master can freely change its behavior. Access to memories are currently only given to the master of the tower.
For those who wish to learn from the old world, or to remember it, there is no other place.
(Think something like the dreams from Inception. And yes, the viewers of the memory can interact with the projections inside, but they are all ultimately memories.)
Remnant Bonus: +20 HP