And open it up. With my Orbit tool running, I'm going to spin around and I'm going to look at the side of the building. I'm going to select my Walk command. I'm going to hit the drop down, and I'm going to actually make sure Collision and Gravity are turned off. I'm going to walk right through this wall as if it wasn't there. I'm going to turn around to the right, and notice that there's a staircase there. To walk up the staircase, I need to turn my gravity on and I need to turn my collision on. Once we do this, we'll no longer be able to walk through a wall. Go ahead and click the drop down underneath the walk icon, and turn on gravity.