Istivin : City of Shadows.
Vault of the Drow
The city of Erelhei-Cinlu dominates the vast cavern known as the Vault of the Drow. Though the Vault, aglow in a purple bioluminescent haze, is six miles long and nearly as wide, the drow city is its crown.It is uncounted centuries old.
Ruled by eight noble houses, each dominated by a high priestess, Erelhei-Cinlu crouches at the center of a web of alliances and rivalries, hidden plots, and ancient traditions that reach through an untold number of tunnels and caverns beneath the world, and on its surface.
Erelhei-Cinlu lies in a huge cavern, over six miles long and nearly as wide, beneath the Hellfurnaces known as the Vault (also known as the Vault of the Drow). A huge chunk of turnkeoite on the ceiling of the Vault gives the appearance of an alien moon, whilst much smaller deposits of other exotic minerals give one the impression of an starry night sky.
Major bodies of water within the Vault include the Pitchy Flow, the Weeping Spring that flows north and west into it, and the Mere of Glooms in the midst of the Weeping Spring.
Much of the Vault is filled with forests of lichens, crystalline growths, and fungi. Merchant estates are scattered south of the city, as are fortresses for the male and female orders of warriors. The city itself is built on the southern bank of the Pitchy Flow in the northern corner of the Vault. A single structure, the Flying Bridge, connects Erelhei-Cinlu with the other side of the Pitchy Flow. Across the river is a plateau containing the estates of the noble houses, and a tunnel leading to the Great Fane of Lolth.
The city of Erelhei-Cinlu is surrounded by a 30-foot-tall wall of seamless polished basalt, interrupted by 40-foot square towers at regular intervals. On the shores of the river, the wall is 50 feet high and without towers; the river wall is the exclusive domain of female soldiers.
The buildings of Erelhei-Cinlu are alien and strangely disturbing to human eyes, its streets narrow and crooked.