The Mystery of Extraordinarily Accurate Medieval Maps Beautifully detailed portolan charts present historians with a puzzle: How were they made? A mathematical analysis offers some clues.

Completed in 1459, the Mappa Mundi is the compendium of all the geographical knowledge of the time and is arguably the greatest medieval map of the world.

Sherif Idris­si’s map was the most accu­rate avail­able *at his time.* Even the Arab world had more infor­ma­tion avail­able by Fra Mau­ro’s time, and Fra Mau­ro did exact­ly what Sherif Idris­si did — gath­er avail­able infor­ma­tion, and plot it onto parch­ment.

The medieval Islamic cartographer and scholar Muhammad al-Idrisi created a world map in the 12th century which remained the most accurate for three centuries. A circular map found in later editions of al-Idrisi's work, this from ‘Alî ibn Hasan al-Hûfî al-Qâsimî's 1456 copy.

With a team of dedicated monks and lay brothers to help him, fifteenth-century Venetian Fra Mauro attempted to create the most accurate map of the world. This week, Danièle speaks with Meredith Small about this incredible mappamundi, what it contained, and how this landed Fra Mauro on the moon.