Information system models often consist of multiple views and semi-structured diagrams, which form both a hierarchical and a network structure. These models should be reviewed in order to find possible faults as early as possible in the development process. A conventional CASE tool shows diagrams in separate windows without any visual cues about how diagrams relate to each other. This might result in design errors, omissions, and inconsistencies. We introduce problem areas and potential solutions on how to visualize interrelationships between UML diagrams. Our research prototype enables exploration within the model, utilizes intelligent zooming (hides and shows details automatically), and shows how diagrams and objects within them could be related to each other by using visual cues.