Mono.Cecil

By grouping files together it is possible to express the architecture in terms of a hierarchical set of directed graphs. Within a graph the edges represent a dependency of one node on another. By clicking on an ellipse in the diagram it is possible to descend to the next level. The top level diagram can be found in Top level.
Given that graphs have been derived then metrics can be calculated for each, these are presented in Summary of graph complexity.
The Doxygen source for the pages and their diagrams were generated by running the tool from my article on CodeProject on the output of a utility that scanned the .NET assemblies of Mono.Cecil. The tool itself resides on Github.