Impossible Figures

We talked in school about impossible figures. I think, they are very interesting, so I build my favorites. Do you know the feeling, when you go up a staircase and don't know, when it ends? This feeling could be on a impossible staircase, because you would go in a circle. But in the second picture you can see that it isn't a circle. I like the impossible waterfall too, because water can't flow upwards, but here it can. There are two more impossible figures. You can see them on the pictures. I hope you like them.