CodeCrawler is the software visualization classic which combines metrics and software visualization, developed by Michele Lanza.
Although CodeCrawler has been discontinued, its visualizations are now an integral part of Moose: a powerful scriptable visualization tool has by far surpassed it. The heir is called Mondrian.
The official CodeCrawler memorial page is located here: http://www.inf.unisi.ch/faculty/lanza/codecrawler.html