The GUIDE system has been developed in order to provide city visitors with an intelligent and context-aware tourist guide. The system has been deployed in the city of Lancaster and integrates the use of hand-held personal computing technologies, wireless communications, context-awareness and adaptive hypermedia. This paper focuses on the role of adaptive hypermedia within the GUIDE system and the techniques used to tailor or adapt the presentation of web-based information. The context used by GUIDE includes the visitor’s personal context, e.g. the visitor’s current location and personal profile, and the environmental context, e.g. the opening times of the city’s attractions. Following a field trial based evaluation, in which positive feedback was received, the system is now publicly available to visitors who wish to explore the city.