Source code investigation is one of the most time consuming activities during software maintenance and evolution, yet currently available tool support suffers from several shortcomings. Browsing is typically limited to low-level elements, investigation is only supported as a one-way activity, and tools provide little help in getting an encompassing picture of the system under examination. In our research, we have developed tool support for design navigation that addresses these shortcomings. A Design Browser allows for flexible browsing of a system’s design level representation and for information exchange with a suite of program comprehension tools. The browser is complemented with a Retriever supporting full-text and structural searching. In this paper, we detail these tools and their integration into a reverse engineering environment, present three case studies, and put them into perspective..