Computer technologies and digital recreations have been widely used in the field of Cultural Heritage in the past decade. How- ever, most of the effort has concentrated in accurate data gathering and geometrical representation of buildings and sites. Only very recently, works are starting to go beyond that approach by including digital people, performing specific rites, acting as guides or merely walking around. The main goal, however, is to depart from the dead, empty reconstructions, and to try to add a new level of realism. In this paper we present a novel use of virtual crowds for Cultural Heritage: we use them to predict behaviors, or to help scholars draw more educated conclusions on unknown matters. We specifically present a case study based on an artificial intelligence crowd simulation which is being used by scholars to study the ergonomics of the Roman Colosseum: it was formerly believed to be an excellent people-mover, but currently that belief is seriously questioned, as potential bottlenecks seem to have been detected. CR Categories: I.6.3 [Computer Methodologies]: Simulation and Modelling – Applications; J.5 [Computer Applications]: Arts and Humanities –