Originally Posted by Greg
I was mainly asking if there were true locations with significant combat, puzzles or loot that were not visited by quests.
If you have the Anarchy Edition there's two sewer levels that are not covered by any quests, which you have to find on your own. One in each of the different wasteland areas. I didn't even find them until my second play through. Both have nice loot and combat. Only after you find the sewer in each part does it appear on the Job Board good for a second trip back in.