On the top floor of the Office building (for example Kavala has at least three of this building type. You can identify the building from this video: http://youtu.be/Spgsw-9wLjg) walking just beside the wall beginning from the end of the stairs it is possible to walk in the air all around the empty space of the staircase. After falling down on the stairs it is also possible to get stuck between the stairs and wall.

Also, before I figured out this wall climbing possibility I did get stuck a couple of times just the same way (between the stairs and wall) like at the end of the video just by running down the stairs close to the wall (this was harder to reproduce. It is possible that the couple of times this happened I actually was running already in air but I didn't realize that then.) {F21667}