Chart of Juan de la Cosa

The "Map of Juan de la Cosa" is a multicolored cartographic document produced by hand. It is drawn on two pieces of calfskin or vellum parchment joined at the center. It is signed and dated, as was usual for portolan charts (medieval cartographic documents), on the narrowest part of the skin in the left-hand margin with a single line: "Juan de la Cosa made this at El Puerto de Santa María in the year 1500." The inscription appears below an image of Saint Christopher. It was common to include religious images on these kinds of documents, usually of the Virgin or the Crucified Christ.

The map's creator, Juan de la Cosa, was a Cantabrian sailor from the town of Santoña who had settled in El Puerto de Santa María. He accompanied Christopher Columbus on his first 2 voyages (and possibly the third) and Alonso de Ojeda on 2 others, making up to 7 trips to the Indies. He died in 1510 at the hands of indigenous locals in Cartagena de Indias in Colombia.

The map is world-renowned, and its importance lies in it being the first cartographic document to represent the New World. It also demonstrates the transition from medieval to modern cartography, serving as a model for the later "Padrón Real" (Royal Register), which was a master map created at the House of Commerce from 1508. Although it lacks geographic coordinates, it shows the equator and the Tropic of Cancer, as well as the meridian that passes through the Azores. The latter was used as a geographic reference to establish the dividing line between Portugal and the Crown of Castile and Aragon in the Treaty of Tordesillas.

Juan de la Cosa must have made the map when he returned from his first expedition with Ojeda, which arrived back in Seville in June 1500. Considering how lavishly the map is embellished, it seems likely that it was a special assignment, possibly from Archbishop Fonseca. He was in charge of organizing trips to the Indies to give the Catholic Monarchs a comprehensive view of the kingdom's new discoveries and an idea of what the new world looked like.