Map Mystery

The Washington Post covered a fascinating seminar about maps...the kind with extraordinary detail that seemed to appear out of nowhere in the Middle Ages. The Portolan maps...

...one of the world's greatest and most enduring mysteries: Where and how did medieval mapmakers, apparently armed with no more than a compass, an hourglass and sets of sailing directions, develop stunningly accurate maps of southern Europe, the Black Sea and North African coastlines, as if they were looking down from a satellite, when no one had been higher than a treetop?

     The story is a great read.