ABSTRACT of "Visualizing Large Cyclic Hierarchies in 3D Hyperbolic Space": There has been a great deal of previous work in visualizing trees. However, many interesting hierarchies are actually more general directed graphs that may contain cycles. The World Wide Web is the most well-known example of a hierarchy where child nodes (documents) may have multiple parents (incoming hyperlinks). Filesystems have always been a favorite example for tree visualization systems, but in fact Unix filesystems can contain cycles in the form of symbolic links. Although these hierarchies are not strictly trees according to the rules of graph theory, it can be very useful to see them laid out in a tree-like fashion. We show the true structure of these hierarchies by also drawing the non-tree connections, or "backlinks." A fundamental problem in drawing trees is that the number of nodes in the structure grows exponentially, but the volume of space in which to place them only grows geometrically. We're forced to choose between a view of the big picture and a close-up view of a small number of nodes. We can get around this limitation by navigating according to the rules of hyperbolic geometry, which gives us an exponential amount of room to work with. We'll see a distorted view of the tree for the same reasons that flat maps of the Earth are inevitably distorted compared to the true shape of the continents on the globe. Conveniently, this distortion is exactly what we need in order to both focus on a node and see its surrounding context at the same time! We're interested in visualizing hierarchies so large that even moving to hyperbolic space doesn't completely solve our problems. We reduce both the visual complexity of the scene and the amount of time it takes to draw it by applying level of detail techniques. Instead of always drawing the entire hierarchy, which might be unmanageably huge, we start by only expanding a limited number of levels down from the root node. We allow the user to navigate through the entire structure by choosing which nodes to expand further or collapse. Nodes which represent collapsed subtrees are distinguished from ordinary leaf nodes by color coding. A related issue of scale is that drawing all the "backlinks" for a large hierarchy can lead to a great deal of visual clutter, especially for the highly interconnected hierarchy like the World Wide Web. We can provide controls to let the user interactively choose which nodes should have incoming or outgoing backlinks drawn. We will present a tool which uses these techniques to support Web site creation and maintenance.