The Undercity was once the lower portion of the great palace of
Lordaeron, holding the crypts of royalty, only to be destroyed in one
moment of madness. Now, the Undercity is occupied by Lady Sylvanas and
her Forsaken minions. Cataclysm has not changed the Undercity much,
however players will be, for the first time ever, able to fully explore
the ruins of Lordaeron. Finally we will be able to get a taste of the
not so distant past when the Ruins of Lordaeron were not just ruins but
instead a grand palace, filled with light and laughter.

Moving through the entrance tunnel into the Ruins of Lordaeron proper
the first thing that caught my eye is the myriad of towers dotting the
horizon just beyond courtyard leading deeper into the city have been
removed, the dome that was once in the background is pushed forward and
the walls on the opposite side of the courtyard are now sporting small
towers.

Get your first glimpse of the changes to Undercity in href="http://www.tentonhammer.com/wow/previews/undercity"
target="_blank">WoW Cataclysm - Undercity Preview.