This is a great shortcut when you and your friends try to get the vidmaster challenge annual.

Before you start making your way up the tower, go to the far right, where you would normally try to get up there, keeping going right until you hit the wall.

There you can climb up to the top, and get 5 steps from the top, and run towards the wall and the 3rd walkway and crouch jump to the walkway.

It saved me and my friends maybe 30 minutes using this shortcut.