Walking trough the Great Wall of China
In this famous illusion, David Copperfield walks straight through the Great Wall of China.
Explanation: I guess nobody really believes that David Copperfield actually went through the wall, but it's still puzzling. How did he get to the other side? The solution might be easyer than you've expected.
The moment Copperfield steps behind the sheets, a switch happens. The shadow we see does not belong to him but to his assistant who is hidden in the unexposed corner and steps into the light right after Copperfield enters the box. He then pretends to penetrate the wall and disappear in it. Actually, he only moves back into an area of the box that isn't illuminated. It is a light effect. He then hides inside of the platform, which is hollow.
Meanwhile, Copperfield opens a secret door in the floor of the box and climbs down into the stairs, which are also hollow. When the stairs are removed (which happens soon after David enters the cage), you can see that the top step is actually under the box. It has a secret door on the top so Copperfield can easily get from the box and into the stairs. Once he is in, the stairs are removed and transported to the other side of the wall where they are used once again. This time, all that Copperfield has to do is get out of the stairs into the box once it is covered by sheets. He carefully gets to the other side of the box without throwing a shadow to the sheets and then pretends to come out of the wall. The illusion is completed.
But what about the arms and the face coming out of the wall?
That's actually the easiest part of the trick. Pay attention to the assistants holding the sheet. Can you see their arms? No. Each of them has one arm under the sheet, one holding a pair of fake hands and the other holding a mask. They press their props against the sheet, creating an illusion of Copperfield trying to come through.