I would guess multiple projectors, an accurate 3d model of the building and skillful art direction. You project a video-textured model of the building over the

I would guess multiple projectors, an accurate 3d model of the building and skillful art direction. You project a video-textured model of the building over the real building. There were some other videos of similar installations floating around the web and they looked quite well even with somehow different viewing angles. For example, here are some with quite large camera pans: http://www.youtube.com/watch?v=X85A1dCpzsI http://www.youtube.com/watch?v=X85A1dCpzsI http://www.youtube.com/watch?v=3h3D6dCLAeo http://www.youtube.com/watch?v=3h3D6dCLAeo People are hardwired to see "3D" based on perspective / shadow hints in 2D images.