Solomon's Library

If one had an interest in demonology and the occult, the pursuit will eventually lead the individual to a Realm referred to as Solomon's Library. A massive plain completely dominated by a series of buildings constructed in a style similar to that found in the city of Jerusalem (as well as other bronze age cities), though bearing almost no sign of wear or aging.
The complex itself is practically a sprawling city on it's own, aided in it's traversal by a series of autonomous canals and gondola's that run like clockwork without assistance. Better than those new trolleys in San Francisco, in my personal opinion. Each building houses great works of magic and engineering that we, as a research collective, still struggle to understand the base facets of any of their operations. The few we have been able to muddle through to at least a minor understanding of still clearly hold deeper secrets and further use that we are currently unable to ascertain.
The name isn't simply a tongue in cheek reference either. Each papyrus scroll pulled from the depths of the extensive catalogue of the many libraries on the premises, and ream of paper (Yes, paper, seemingly developed completely separate from out modern paper) is written by one figure.
Solomon. Plucked straight from the stories my Sunday School teacher used to tell me before I ran away from home. His seal is stamped directly upon each page, as if to ward off those that aren't supposed to seek his knowledge without his permission.
To say I appreciate that the page doesn't burn my hands as I hold them now would be an understatement.
On the surface, the academic nature of the Realm is apparent and overwhelming. How could you not be distracted by the arcane instruments that seem to turn our understanding of reality and magic on it's head so effortlessly? At the center of it all, however, is a massive granite cube, a capstone, sits as the centerpiece of a huge raised dais.
Upon each visible face of the cube, Solomon's seal is again carved. These examples, however, are clearly infused with magic of several descriptions. The weaving of the Lorewinds is so tight, and the myriad of winds of magic tied together so large, the exact spell is nearly impossible to pick apart.
Our original hypothesis was that the capstone was the anchor through which what we thought was an artificially created Realm was maintained. We still don't have definitive proof of the realms... organic or inorganic origin, but we do know that the capstone is not an anchor.
It is a doorway.
It took us years to learn this fact alone, and years longer to finally pry the command words from the lips of the spell itself and piece it together through the miles of writing Solomon left behind.
When spoken by someone of sufficient magical power, the stone rises from it's resting place and remains hovering in the air, it's suspension sustained by the magical energy of the person (or persons) who spoke the command, only stopping the drain when the command is spoken again. When the process is finished, a staircase is revealed that spirals downward into the dark.
Should one traverse the stairwell, it will quickly enter into a large open chamber, cylindrical in shape and covered in arcane symbols both carved and painted upon it, before the stairwell is the only thing that protrudes from the wall until it reaches the floor of the chamber, where once again the symbol of Solomon is carved. Speaking another command (one that was equally as hard to acquire as the first, I might add) The floor of the chamber reveals itself to actually be a magically powered elevator as it starts to descend even further, revealing the numerous containment cells that Solomon constructed to keep the guests he was most famous for from ever getting loose.
A legion of demons.
Each cell is built directly into the wall with the elevator in mind and as such the shaft maintains the cylindrical shape perfectly all the way down. Each cell is precisely carved out into a regular shape, about twenty feet deep and fifteen feet tall, and equally pasted with arcane symbols as the entranceway. The over 90% of the cells that are occupied are all sealed with some sort of energy barrier sustained by magic generated somewhere within the Realm itself. The many demons within, which we don't dare release based on our lack of knowledge about them seem weakened and made far more docile by the nature of their cells, falling in line with Solomon's legendary command. Often times they don't even acknowledge our presence as the elevator passes.
Remaining on the lift until it can descend no further, you will find that the rings of cells eventually stop before you reach the bottom, leaving you to stare at stone walls until the elevator has traveled another fourth of the distance it had when the cells stopped appearing. After that distance is crossed, you finally reach the bottom of the prison tower.
Around the elevator, still constructed so as to be perfectly in line with the elevator shaft are eight arch shaped carvings. Seven massive pairs of doors, six of which are sealed shut with chains and locks made of an unknown metal on top of the arcane markings that should now simply be expected, and one large message presented as what a coworker of mine described as being similar to the Egyptian cartouche. The seventh door remains closed, though the chains and lock around it are open and hang impotently down towards the floor.
The 'cartouche' I mentioned is a message seemingly left behind by the original creator of everything in the realm, written in ancient Hebrew, of which I will transcribe to the best of my abilities.

Abandon All Hope Those Who Have Entered Here

These doors, sealed as God asked of me, contain seven demons of strength innumerable.

So great is their power that I, who has fought Asmodeus and Belphegor, and stolen knowledge from the libraries of Lucifer and Leviathan can be confidant that I would be able to match them.

To keep them from damaging our world irreparably, I have sealed them through great effort and personal cost in these seven tombs and will spend the remainder of my lifespan attempting to destroy them.

For the benefit of those who might find my work, should I fail, I name these demons.

---

Kizum, Enslaver of the Seven Stars

Ammit, Obliterator of Nations and Eater of Crowns

Nariyu, The Chill Wind Creeping

Galgos, Fell Rider of Torment

Náströsston, Devourer of Cradles

Mannalan, She Who Defiles Graves

Totphe, Thief of Man's Future

---

Each of these creatures are a match for the rest of the demons locked within this tower combined, and I dare not add to their power even by feeding them demons who's power is poultry in comparison.

As such, I am forced to try and destroy them with the other skills at my disposal.

All shall remain sealed, bar the one I am attempting to banish, yet it's door shall remain partially locked until I succeed.

If you have come across this place and the doors remain closed and bared, I implore you with the most sincerity an old King can muster.

Leave these doors locked and sealed and protect this place with everything you can for the good of our peoples, and their children.

May the Many Faced God have mercy on me for this task I undertake.

May the Many Faced God have mercy on us all. 

Type

Dimensional plane