Numerous techniques have been developed for visualising hierarchically structured information. This paper presents a new framework for the visualisation of hierarchies called the hierarchical visualisation system (HVS). HVS is a general framework implemented in Java. It provides a synchronised, multiple view environment for visualising, exploring and managing large hierarchies. HVS reads hierarchies either from the file system or from TreeML files. Eleven hierarchy browsers have so far been implemented within HVS, including: traditional tree views, the classic Walker tree layout, information pyramids, treemaps, a hyperbolic browser, sunburst, and cone trees. In addition to being a tool to explore and manage hierarchies, HVS was also designed to provide a platform for the empirical evaluation and comparison of different hierarchy browsers. The hierarchical visualisation testing environment (HVTE) is a semi-automated testing environment built on top of HVS. HVTE is being used for a series of comparative studies of hierarchy browsers.