Recommendations for C++ sourcecode analysis tools

[Michael ODonnell]

I've joined an established project and I'm trying to come up to
speed with their (complex!) C++ code and could use some help
in divining how all the pieces fit together.  I'm doing all the
usual WWW searches but also wanted to get recommendations from
the GNHLUG; anybody know of good sourcecode analysis tools for C++
that run on Linux?  We already have ctags and Cscope and though
they're occasionally (accidentally) useful they're basically
not up to the task of grokking all the class hierarchies and such.