Dibella's Watch adds an entire new continent to Oblivion. It comes complete with a major city, castles, towns, villages, farms, monasteries and all the good stuff that makes up a Medieval landscape. There's also fighting to be had and quests to be made!
There's only one Ayeleid Ruin in Dibella's Watch, and that's found out west. in Beta 09, you can visit its exterior. The interior is not yet done.