Pelagios is a collaborative effort involving over 30 scholarly websites about ancient art, archaeology, history, and literature. It is co-organized by scholars at the Open University, the University of Southampton, and the Austrian Institute of Technology. Participating projects use data from the Pleiades gazetteer to connect their contents geographically, making it easier for users to find information related to individual places in the ancient world.
The Pelagios heat map on this page can be zoomed and panned to focus on an area of interest. A single mouse click launches a popup for the closest place. "References" links on the popups will take you to pages on the Pelagios site summarizing the data available and giving you links to corresponding records on each partner project's site. You can also use the search box in the upper right-hand corner to find places on the map by name.
Pelagios phases 1 & 2, dedicated to classical antiquity (Greece and Rome) were funded by Jisc. Pelagios 3, which extends the methodology to cover medieval Christian, Islamic, and Asian geography, is funded by The Andrew W. Mellon Foundation. You can read more about the scholarly functions of the project via "Pleiades and Pelagios: Organizing Ancient Geography on the Web." Work in progress is discussed on the Pelagios Project Blog.