Zilkhûn is an Underdark city situated within Batwor. Constructed by the Khazarkar Empire half a mile beneath their capital city of Nibar-Pharân, this city was built at great expense and through the use of magic. It serves as a rival commercial port to Bandunazân and Balmoloch. Prior to the city's establishment, a harbor was excavated and a channel was carved eastward, culminating in the breaching of a coffer dam to allow the Erethor Sea to flow in, creating an underground port connected to the surface.
Zilkhûn and its maritime channel lie at the foot of the Khirrêth Plateau.