There is a third base of the Titans named Ulduar. Warcraft RPG: Shadow & Light—page 107, says Ulduar is located at the Storm Peaks of Northrend Continent. Northrend is not yet part of World of Warcraft MMORPG.  Northrend will possibly be available in a future expansion pack after Burning Crusade expansion.

The Storm Peaks are an important place in Warcraft History.  800 years ago, Aegwynn the Guardian of Tirisfal, mother of Medivh, united forces with the dragons to fight the Burning Legion.  The demons’ mission was to drain magic from the dragons to initiate a new invasion of the Burning Legion.  However, Aegwynn and the dragons defeated the demons.

Enough magic was drained to summon a tiny portal that allowed Sargeras’ avatar to enter Azeroth.  It was at the Storm Peaks of Northrend where the epic-legendary battle between Aegwynn and Sargeras’ avatar took place.

The tale of this battle may be read in detail in Warcraft: The Last Guardian, when Khadgar sees a vision of the past within the Tower of Kharazhan.

A very substantial source to read about Ulduar may be found in World of Warcraft: Lands of Mystery—released on April 3, 2006 by White Wolf Publishing.

The residents of Ulduar are the Storm Giants—created by the Titans. The Storm Giants are low in numbers nowadays. Brann Bronzebeard calculates nearly 150. To have labor support, the Storm Giants created constructs to help gather minerals and to guard Ulduar. These constructs are named Crystalline Golems. Places of interest in the Storm Peaks are Ulduar and the Temple of Storms—Titan-made building far to the west of Ulduar.  There is more info in the RPG Book.