Why?
Hexen and Heretic has a great story. http://www.ravengames.com/hexen/story-world.php
Heretic http://www.ravengames.com/heretic/story.php
also doom wiki is cool http://doom.wikia.com/wiki/Entryway
also they have released a new hexen mod
looks pretty sweet if you like the original heretic & hexen using doom3 source engine
http://www.hexenmod.com/about.php