Ok that last one triggered my memory I think...if you go up that ladder and around, you'll be in this big cylindrical shaped room, as you can see in the pics...IIRC, there is an exit somewhere...lemme get into the game right now and post back in a few mins.
Yup you are correct, but notice that when you go up the ladder and go across the "tightrope walk", that you go over a large divider, simply drop down on the other side of the wall in the cylinder room and out the door below.