We present a Web-based application that allows a user to walk through, see, and interact with a fully three-dimensional model of an old Mexican city. The city itself motivates this work. Campeche is of enormous historical value and has been placed by UNESCO on their list of the world cultural heritage sites. A virtual visit can benefit both tourists and scientists. We show how the model was created and how certain technical issues were addressed. The application runs interactively over a modem-based connection. It first displays primary visual clues and refines the details later. A data prefetcher loads the potentially visible data in advance. The system loads data from the neighborhood by which the user passes using the VRML proximity sensors. In such a way it loads the local neighborhood of the location of the visitor in advance. The application is context-sensitive and can display additional textual and image information.