This set of maps by the Genoese mapmaker Pietro Vesconte forms a supplement to a work by the Venetian author Marino Sanudo entitled Liber secretorum fidelium crucis (the book of secrets for faithful crusaders). This was a treatise written for Pope John XXII in order to promote a crusade to the Holy land in 1321. The maps consist of a ‘mappamundi’ world map drawn in the style of a sea chart, five portolan sea charts of the coasts of Europe and North Africa, culminating in a map of the Holy Land.