Telnarquel

Telnarquel, also called The Hidden City, was a city in the Underdark that was so well concealed that some drow explorers refused to believe that it actually existed. In truth, it did indeed exist but was abandoned for an unknown reason at some point during the 14 century DR. It lay empty for a few decades until an alhoon made the city its lair.

Rumors & Legends
Dove Falconhand once claimed to be from Telnarquel for a cover identity while polymorphed as a drow infiltrating a large group of Vhaeraun-worshipers who were covertly invading Scornubel in 1369 DR.