An approach for metrics-based tool support for the task of understanding object oriented software systems is presented. It stresses the combined presentation of structural information and of different types of metrics in hyperdocument form for the identification of large and small system components and usage and inheritance relations of the system components with each other. A small exploratory experiment is described which was used to validate our approach; in this experiment, both our tool and other approaches were used to restructure given software systems into subsystems. Although we had to make some restrictions within this experiment and had to assume some axioms for interpreting the results, our basic assumptions have been confirmed.