Some years ago, Francesco Scavullo was on location at a pyramid in the Yucatan. He ran up the hundreds of narrow steps and at the top explored camera angles for his shoot the next day. When it was time to come down, he froze - the height terrified him and the steps seemed to have become narrower. For five hours, he refused to move.At dusk, his colleagues finally sent someone to rescue him. He crawled down back-ward, gripping the stairs so hard that his fingers were bloody.