Rome, Italy - April 21, 2013: Actors from Legio XI Claudia building a Testudo, the powerful Roman attacking formation, during the battle taking place in Circo Massimo, Rome, for Rome's Foundation Celebrations. The event has been organized by Gruppo Storico Romano and involved 11 different countries, 2000 people and 53 different volunteer associations. All the costumes are historically correct thanks to the supervision of a team of archeologists and researchers. The leading volunteer group of Gruppo Storico Romano was born in 1994. By now, the group has highly increased and has a scientific department of experimental archeology which expresses itself by recreating ancient situations such as parties or gladiators' fights and dances.