In this paper we address the task of human-robot interaction in public mass exposition with several autonomous robots at a time. This implies questions regarding multi-robot control and interaction management with respect to social and commercial aspects of such an exposition. Multi-robot and interaction management is addressed with respect to visitor density and visitor flow. Human-robot interaction is modeled using the SOUL environment. Concluding we will present and discuss results from the Swiss national exhibition Expo.02 in the time from 15.05.02 to 20.10.02, with over 10’000 hours of total robot operation time and more than 600’000 visitors.