"There is no room for error and everyone knows what they have to do," says Sonia Allienne, a stagehand at the Paris Opéra Bastille. The stage on which the plays are performed is also a giant lift that allows the gigantic sets to be lowered to the basement for assembling and disassembling. "We need four to five hours to completely make the change," says Lionel Morin, head of the Bastille machinery, the largest in Europe. IMAGES AND SOUNDBITES