In the "Treasury level, it is possible to get up on the roof of the treasury. Have your pistol or grenade equipped in order to run faster, then run directly at the back door and dive into it. Do this by running and rapidly clicking the Right Analog-stick. Do this so your head hits the door and you "teleport" to the roof. This also works on the level with the wall. You can "teleport" up into the rooms on the ends of the wall. Note: This may require some practice and should work with any building with an overhanging ledge that you can dive under.