Portolan charts are navigational maps based on realistic descriptions of harbors and coasts. They were first made in the 1300s in Italy and Spain. The word portolan comes from the Italian adjective portolano, meaning "related to ports or harbours." These charts, actually rough maps, were based on accounts of medieval Europeans who sailed the Mediterranean and Black Sea coasts. Frequently drawn on sheepskin, portolan charts show coastal features and ports. The straight lines criss-crossing many p… (More on Portolan)