| In the AD&D game world of Greyhawk, the subterranean city of the dark elves (Drow), as detailed in module D3, Vault of the Drow. This is the Greyhawk cognate of Menzoberranzan in the Forgotten Realms setting. The city lies in a great cavern, the ceiling of which is speckled with peculiar minerals. With ultravision, this gives the effect of a starry sky, and there is one big chunk that serves as a moon. This adds to the land's distinctive faerie charm. Visitors are given cloaks that show an unusual color to creatures with ultravision (including Drow), similar in function to the corporate "visitor badge". Humans also receive spectacles that confer infravision, since Drow do not tolerate normal light sources in their domain.
While Drow are notoriously xenophobic, pragmatic concerns require them to permit trade with other races: kuo-toa, illithids, and the odd surface-dweller. Deep gnomes (svirfnebli) are bitter enemies of the Drow; only a ballsy renegade svirfneblin would trade in Erelhei-Cinlu, and they had better employ a crack team of bodyguards during their stay in the city. It is common for unwary visitors, particularly individuals foolish or unlucky enough to become separated from their companions, to be robbed, murdered, or enslaved.
The markets of Erelhei-Cinlu are a great place to get stuff you just can't find on the surface: adamantite ore, rare fungal preparations, finely crafted hand crossbows, and magic unique to the Drow and their Deepearth trading partners.
At the center of Drow culture is the worship of the Demon Queen of Spiders, Lolth, and at the center of Erelhei-Cinlu's politics is the Great Fane of Lolth. This temple occupies a side cavern, called The Egg of Lolth; the area is forbidden to non-Drow. The high priestesses of Lolth may contact her directly here, and summon her demonic handmaidens, the nightmarish yochlol.
The noble houses of Erelhei-Cinlu include:
Aleval, Baenre, Despana, Eilservs, Everhate, Kilsek, Noquar, and Tormtor. The house of Eilservs is unusual in that they revere the Elder Elemental god, Ghaunadaur, rather than Lolth. They were the instigators of the giant raids in the G1-3 "Against The Giants" module series. | 
