During the execution of software systems, many crashes and exceptions may occur, and it is a real challenge to understand how a software system is behaving. By exploiting the data recorded during the execution of software systems, one can discover architectural models to describe the actual execution of software. An architectural model typically structures a software system in terms of components, interfaces and interactions. The discovered models provide extensive insights into the real usage of software, enable new forms of model-based testing and improvements. In addition, replaying execution data on such models helps to localize performance problems and architectural challenges.