Readers with an interest in medieval history and maps, as well as those who delight in quirky historical facts, may enjoy exploring Historia Cartarum. This intriguing site is the creation of John Wyatt Greenlee, a doctoral candidate in medieval studies at Cornell University whose "research is primarily driven by questions of how people perceive and reproduce their spaces: how movement through the world both experiential and imagined becomes codified in visual and written maps." At Historia Cartarum, readers will find several of Greenlee's digital history endeavors under Projects in Progress. One of these is the award-winning Mapping Mandeville Project, which offers an interactive map where text from the 14th-century book The Travels of Sir John Mandeville is overlaid onto a reproduction of the 13th-century Hereford Map. Another fascinating undertaking is the Eel-Rents Project, an outgrowth of Greenlee's dissertation research. This project examines the role of eels and their widespread use as a currency in the medieval English economy from the 10th to the 17th centuries. In addition to an interactive map, the Eel-Rents Project also includes Greenlee's exploration of the distances that eel-rents may have traveled and what an eel-as-currency would likely be worth in modern terms.