One of the most beautiful maps to survive the Great Age of Discoveries, the 1513 world map drawn by Ottoman admiral Piri Reis is also one of the most mysterious. Gregory McIntosh has uncovered new evidence in the map that shows it to be among the most important ever made.

This detailed study offers new commentary and explication of a major milestone in cartography. Correcting earlier work of Paul Kahle and pointing out the traps that have caught subsequent scholars, McIntosh disproves the dubious conclusion that the Reis map embodied Columbus's Third Voyage map of 1498, showing that it...