V'elddrinnsshar was a drow city located on a mile wide island in the centre of the Moondeep Sea. The city's name seems to be composed of two drow words that have been given translation (Veldrin and shar meaning concealment and mind respectively) and thus the name could mean Concealed Mind or some variation there upon. 
Like most drow cities, it was dominated by the clergy of Lolth, but even her divine magic couldn't protect her subjects from the Ascomoid Plague. The last inhabitant died in 1278 DR and nothing was heard of the place until ten years later when duergar looted whatever remained.
In 1337 DR a priestess of Kiaransalee named Larynda Telenna brought with her a group of acolytes who aided her in constructing the Acropolis of Thanatos in the ruins of the city. The black marble temple attracted a thousand more of the faithful and since then, it has been used as a base from which to launch attacks on the cults of Orcus that inhabited Vaasa above them. Little do the drow know, but without them, Gareth Dragonsbane may not have been able to defeat Zhengyi as readily as he did.