Description- These ruins once held a flourishing civilization, but for reasons unknown, all has been destroyed, and the cursed and ruined remains of the city are now inhabited by scores of dark creatures. (Fiends and Undead)

It is at the beginning of T3, so the difficulty would be between the Royal Jelly/Roarmulus Twins and Vanaduke.
The area is mostly a huge maze of areas filled with cracked and broken temples and walls.
The backround would be shadow mist and darkness. On one of the levels though, halfway through the player enters a large mostly intact temple, where there is a large fight, afterward the level is almost over.

Monsters included:
Devilite
Trojan
Greaver
Silkwing
Zombie
Spookat
Pit Boss
Devilite Overtimer
Ghoulish Crawler

Unique objects-
In some ares, the Crawler's "egg pod"-like objects will lay around. I they are hit or a Knight comes too close, they will explode, dealing minor damage over a small radius and releasing 3-5 Greavers.

Level name-
Depth 19- Cadaverous Courtyard- contains mostly Zombies, Kats, and Greavers, a few Devilites, mostly open area
Depth 20- Egg Chambers- contains huge amounts of egg pods and Greavers, also many Devilites; is a dark hive-looking area
Depth 21- Temple of the Trojan- Level described earlier with temple, Large battle in temple at very end, final wave have 5 Trojans. Has all monsters listed

Sorry I have to go urgently, but I will continue on next post.