Portolani or portolan maps are ancient nautical charts first made in the 13th century around the Mediterranean. They later expanded to include other regions and are noted for their high cartographic accuracy, notwithstanding the very limited technical means available.
Some of the most noticeable characteristics of portolan maps are the network of ‘star shaped’ compass lines, the symbolic representation of well-known harbors and sites, a craggy coastal line and symbols pointing out shallow and/or dangerous nautical zones.
Portolan maps gave sailors a relatively accurate image of the coastlines and were used as a tool to navigate smaller bodies of water. So long as seamen did not sail oceans these maps gave sufficient guidance. Due to their beautiful drawings and the craftsmanship needed to make these maps, many scholars believe they served decorative purposes as well.
The oldest preserved portolan is the ‘Carte Pisane’ and is estimated to have been drawn in 1290 and is preserved in the Bibliothèque Nationale de France in Paris.