The abstract art of Xenakis keeps on taking shape. In 1971 happened the fifth edition of the annual festival of Arts of Shiraz-Persepolis. Xenakis is invited to create the opening ceremony. From this invitation, an open-air Polytope will be born. The program: a sound and light show in the ruins of the ancient fortresses of Emperor Darius II. The public stands and moves among the six listening poles formed by eight loudspeakers, each broadcasting a track of the soundtrack. This one contains Diamorphoses (7 minutes), followed by Persepolis (56 minutes). As for the light, the choice is prolific: two laser beams, anti-aircraft projectors, large oil fires scattered on the hill in front of the ruins. 150 children carrying torches walk through this space. The show took place only once, on August 26, 1971. On this occasion, Xenakis accepted a commission from the Empress of Iran, Farah Diba, to create the architecture of the Cité des Arts. However, the reactions of the local press following the Polytope show caused a violent polemic that Xenakis was unable to accept. Five years later, he will decline the proposal for a second Polytope in Persepolis, distancing himself from the increasingly authoritarian Iranian regime.