The medieval nautical chart known as a portolan served as a basis for the planisphere’s design. Portuguese for “concerning ports or harbors,” the portolan was useful for close-to-shore navigation.

A key aspect was the wind rose network: 32-point circles that defined sailing courses, of which there are numerous examples on the “Cantino Planisphere.” During the 15th century, as Portuguese ships ventured ever farther south along the coast of Africa, their pilots developed a return route in the open ocean that avoided unfavorable winds.

With horizons expanded to include the New World, and inclusion of latitude lines to assist with open-ocean navigation, the “Cantino Planisphere” marks a key moment in the evolution of maps from a local to a global perspective.

Brazilian coastline Discovered by Portuguese explorer Pedro Álvares Cabral in 1500, it is depicted on the map with parrots and tropical jungle.

The Tordesillas Line “This is the border between Castile [Spain] and Portugal.” The demarcation line was set in 1494 in Tordesillas, Spain.

Caribbean Islands The “Antilles of the King of Castile.” A Castile flag flies near Santo Domingo, capital of the modern-day Dominican Republic.

Africa Founded in the 1480s, the Castle of São Jorge da Mina, which still stands in Ghana today, played a major role in the transatlantic slave trade.

Mountains of the Moon Mentioned by Ptolemy as the source of the Nile, these legendary mountains are here placed considerably farther south.

Persian Gulf Only a rough outline is shown, depicting the gulf as a large, rectangular lake.