I'm not sure which door you can't get through. Several open with levers on the wall. There is one door which you will only be able to open after creating a magic portal using magical orbs. As you go through the catacombs there are books and manuscripts lying around which often give clues about where or how to go next. As for the barracks it will take a while to get there. Do the catacombs 1st and optionally though I think advisedly clear the woods all around Aleroth and the path south before you get anywhere near the barracks. You'll get more exp that way.
Cleglaw
The question is not, Can they reason? nor, Can they talk? but, Can they suffer?
~Jeremy Bentham
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