On a public street, Criss Angel has himself covered by a large trash can. Moments later, the trash can is removed and Angel is gone. Someone in the crowd points, and there is Angel standing on top of a building, looking all cool.
The trash can that is used to cover Angel has a plastic garbage bag for a liner. Studious students of magic will wonder about this -- who the heck puts a liner in a full-size garbage can? Indeed, it is this liner that makes the trick work.
Once he is under the garbage can, Angel uses a flashlight and a pocket knife to make a slit in the liner. He then gets into the space between the liner and the outside of the trashcan. The people turning the trashcan right-side up don't notice the extra weight because excitement has pumped them full of adrenaline, and the crowd doesn't notice that the liner no longer goes to the bottom of the trash can because, as any good street magician knows, crowds pretty much never notice anything.
After the can is upright again, all that remains is for Angel to slip out of the can, run across the street, and use the staircase to get to the top of the building. He can do this at full speed, because when he reappears to the crowd he will be at such a distance that nobody will know how seriously he is panting and sweating.