Get the 2 pillars from either side of the exit where you came from before the cinematic played. You have to drop one pillar on top of the other... you can do this by stepping on the "elevator" briefly and then jumping back out of it. This makes the elevator lower itself below. Push one pillar down to land on the "elevator" below, and then quickly push the other pillar to land on top of the other. It's all a matter of positioning the pillars between the platform and the ledge on the wall.
