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!
The Seldora Monastery is the home of holy men and friars. They keep a nice church going there, in honour of the Goddess Dibella. The church itself was added to the mod with Beta 07 and is of historically accurate early medieval architecture and style.