In program execution visualization, we wish to show where the action is unfolding when some high level use-case is played on the system. However, an important problem is to deal with the volume of data to display. One solution is to represent the architecture of the software in some familiar form. Then we proposed to represent it as a modern city, with buildings and districts, in a 3D space. In this paper we present the way the program execution is represented in such a space and we show how the understanding of this execution is facilitated. Since the display of the full execution trace is impossible because of its sheer size, we developed a trace segmentation technique. Then an information filter, called class omnipresence, is applied to further reduce the information to display. Finally, the resulting sequence of segments can be “played” on the screen, like in a movie.