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 waterfall and lake area at Wordham village were actually designed with an early screenshot from Elder Scrolls 5 Skyrim as source for inspiration.
Nice place