I believe the dark lines are mostly walls but some are barrel racks, bookshelves, or just decorations.

You start bottom, middle in the main hall of the burrow. Turn right and go to the top right corner (through the bookcase) of the hall map to get to the Attic.

Straight to the back of the Attic, turn left and out the door. This will put you back in the same spot where you went into the Attic.

Leave this little room and go straight across the hall to get to the Cobwebbed Wing. Turn right and left and go through the doorway ahead of you, one or two spiders will knock you down along the way. The way out is on the left.

In the Creeping Wing, you’ll go through the first doorway on the left and through the door in the top right corner of the room.

The dreaded Basement. (Yes, I still get turned around in there.) This one is tricky but keep in mind that you’ll make a U-Turn at the end of the hall and another U-Turn at the end of the next hall. Go through the last door on the left.

When you get back to the Main Hall, go straight through the doorway in front of you, the lights go out! Make a left, a few steps and right and the lights come back on. Go through the door at the back of the room.

You’ve made it up to the basement of Bag End! Turn left and follow the hallway around to a door straight ahead. Go through that door and you’re in Bag End proper. Immediately about-face and go through the door behind you to see Lobelia griping at whichever poor soul has become the subject of her ire.

If you’ll make this run a couple of times before accepting quests, it’ll help you get familiar with the twists and turns. Keep in mind that this is the WHOLE run with no quests to move you off the main path. The map in the wiki shows you where everything is (but not how to get to them). I’m hoping to add maps of each room a little later.