ct In this paper, we describe the VesaliusTM Project, a multi-modal collection of anatomical resourcesunder development at Columbia University. 1 Our focus is on the need for navigational tools to e ectively access the wealth of electronic information on anatomy, including life-like 3D images of anatomical entities that can be interactively viewed and browsed. We describe a key component which must be in place in order to develop a exible and reusable digital library system, namely an anatomical knowledge base containing a `nucleus' of anatomical information speci cally designed to make it possible to develop a wide spectrum of curriculum applications that use and extend the information in the knowledge base. The unique contribution of our research lies in the dual focus on user needs and on e ective use of knowledge representation theory in order to develop a system that makes it possible to take advantage of interactive 3D models and the wealth of other anatomical data now avail...