Understanding complex software systems requires getting insight in how system properties, such as performance, trust, reliability, or structural attributes, correspond to the system architecture. Such properties can be seen as defining several ’areas of interest’ over the system architecture. We visualize areas of interest atop of system architecture diagrams using a new technique that minimizes visual clutter for multiple, overlapping areas for large diagrams, yet preserves the diagram layout familiar to designers. We illustrate our proposed techniques on several UML diagrams of complex, realworld systems. CR Categories: I.3.4 [Graphics Utilities]: Graphics editors— Paint systems; D.2.2 [Design Tools and Techniques]: Modules and interfaces—Computer-aided software engineering