The Fane of the Eye was a large cavern complex deep under the Dessarin Valley. It was centered around a black ziggurat temple built by renegade drow and dedicated to the Elder Elemental Eye. Many prisoners were kept here, including Balix.
The cult that built it eventually died out or were hunted by drow loyal to Lolth. The complex remained abandoned until Vizeran DeVir found it and used it to forge the weapons Ironfang, Drown, Tinderstrike, and Windvane. He left the weapons there until the Fane of the Eye was found in 1491 DR by the latest incarnation of the Cult of Elemental Evil.