We perform knowledge discovery in software archives in order to detect refactorings on the level of classes and methods. Our REFVIS prototype finds these refactorings in CVS repositories and relates them to transactions and configurations. Additionally, REFVIS relates movements of methods to the class inheritance hierarchy of the analyzed project. Furthermore, we present our visualization technique that illustrates these refactorings. REFVIS provides both a class hierarchy layout and a package layout and uses color coding to distinguish different kinds of refactorings. Details on each can be displayed on demand using mouse-over tooltips. Finally, we demonstrate by case studies on two open source projects how REFVIS facilitates understanding of refactorings applied to a software project.