Transportation maps are among the most important and influential cartographical works in the world. The Internet is a very important medium for the acquisition and dissemination of spatial information due to the overwhelming popularity and power of the World Wide Web (WWW). In this process of spatial information, the map plays a pivotal role and is multifunctional in its involvement. It retains its traditional role of providing insight into geospatial patterns and relations, while also acting as an interface to other geospatial data. Many new cartographic challenges are raised in developing WWW-based maps to provide visualizations of real world phenomena such as public transportation network systems. This chapter describes the publishing of public transportation maps and the cognitive processes involved in understanding public transportation maps within the medium of the Web browser. It also addresses the cartographic challenges involved in presenting Web-based maps so that users may use the maps for orientation and navigation in unfamiliar transportation systems. The chapter surveys several Internet based public transportation journey planning systems, and also analyzes and evaluates their implementation of maps. Â© 2003 Elsevier Ltd All rights reserved.