The Forgotten Realms have been around for ages. They were originally devised, as I recall, in the early 1970s by Ed Greenwood, before D&D appeared on the scene. It appeared in Ed's articles in Dragon Magazine before TSR obtained the rights and began publishing separate Realms products. Steven E Schend, Eric L Boyd and various other talented writers have helped make the Realms what they are.

Features of the Realms include:

Elminster and Khelben, noted archmages.
Drizzt Do'Urden, the renegade drow ranger, and his magical panther, Guehwyvar.
Menzoberranzan, the fearsome drow city from which he fled.
The City of Waterdeep, home to Khelben, as well as to numerous other famous characters.
The fallen city of Myth Drannor, now infested with demons and undead.
Numerous gates and portals which allow those in the know to travel great distances at speed.
Finder Wyvernspur, the Nameless bard who slew Moander and became a god.
The city of Baldur's Gate, home to the computer game of the same name, although, to be fair, it's a whole lot more interesting than the CRPG allows.

This is part of my idea to node AD&D worlds, and will be updated whenever I think of something good to put in.