Special effects reached a new and outrageous level during these "Wall" shows. For example, a long, high wall made from 340 white bricks was built between the audience and the band during the first half of the show. The final brick was placed as Roger Waters sang "goodbye" at the end of the song "Goodbye Cruel World". For the second half of the show, the band was largely invisible, except for a hole in the wall that simulated a hotel room where Roger Waters "acted out" the story of Pink, and an appearance by David Gilmour on top of the wall to perform the climactic guitar solo in "Comfortably Numb". Other parts of the story were told by Gerald Scarfe animations projected onto the wall itself (these animations were later integrated into the film "Pink Floyd: The Wall"). At the finale of the concert, the wall was demolished amidst sound effects and a spectacular light show.