In the Southern Shelf area there is a mini "fort" for lack of a better term next to the small bandit town (near the first Handsome Jack audio recording). Inside the bandit town there is a drawbridge that is up and a sign that says "scram". Drum music can be heard around this area. It appears to be the only way to access the adjacent "fort", but I can't figure out how to make the bridge drop so I can cross. I also can't find any reference to this area anywhere on the internet.