Cartography and Maps in the Age of Exploration

The cartographic revolution of the fifteenth and sixteenth centuries was the result of three traditions, not one. The first was the rediscovery of Ptolemy’s Geographia and its coordinate mathematics. The second was the empirical practice of Mediterranean and Atlantic pilots, encoded in the portolan charts. The third was the flood of new geographic information pouring in from the Portuguese, Spanish, Dutch, and English voyages. The argument of this page: the maps of the Renaissance are best understood as the reconciliation of these three traditions — and the reconciliation was neither smooth nor complete. J.B. Harley and David Woodward’s History of Cartography (University of Chicago Press, 1987– , six volumes in progress) is the indispensable reference, and Matthew Edney’s Cartography: The Ideal and Its History (2019) is the best short treatment of what cartography actually does.

The conventional story of the cartographic revolution — Ptolemy recovered, America added, Mercator projection invented, scientific map triumphant — is, in its standard textbook form, too neat. The recovery of Ptolemy in the fifteenth century was important, but Ptolemy’s coordinates were often wrong, and Renaissance cartographers had to choose between Ptolemy’s authority and the empirical observations of pilots. The portolan charts, with their accurate Mediterranean coastlines, were the working documents of navigation in the fifteenth and sixteenth centuries, and the great world maps of the Renaissance were often hybrids: Ptolemaic in projection, portolan in coastline, and full of new world information in the margins.

Ptolemy and the Coordinate Tradition

The single most important event in the history of Renaissance cartography was the recovery of the Geographia of Claudius Ptolemy. Written in Alexandria around 150 CE, the Geographia was a comprehensive treatise on mathematical geography, including instructions for drawing maps of the entire known world using a coordinate system of latitude and longitude. The work was lost to Western Europe in the early Middle Ages but survived in Arabic translation, and a Latin translation was made from a Greek manuscript in Florence in 1409. The first printed edition appeared in Vicenza in 1475; the Bologna edition of 1477 was the first to include twenty-seven new regional maps, and subsequent editions in Rome (1478) and Ulm (1482) expanded the corpus.

Ptolemy’s Geographia transformed European geographic thought in three ways. First, it established the principle that a complete map of the world should show all known places in their correct relative positions, rather than serving as a symbolic diagram. Second, it provided a coordinate system of latitude and longitude that became the standard grid for all subsequent maps. Third, it included instructions for projecting the spherical Earth onto a flat surface — the foundation of all mathematical cartography. The twenty-seven maps of the 1477 Bologna edition became the model for the world maps of the fifteenth and sixteenth centuries.

Ptolemy’s geography also contained significant errors. He underestimated the circumference of the Earth — an error derived from the earlier Greek geographer Posidonius, whose value displaced the more accurate measurement of Eratosthenes — and he exaggerated the eastward extent of Asia. Combined, these errors led fifteenth-century Europeans to underestimate the westward distance from Europe to Asia. Christopher Columbus, who used a version of Ptolemy’s estimates and converted the longer Roman mile into the shorter Arabic mile in his calculations, calculated that the distance from the Canary Islands to Japan was about 2,400 nautical miles, when the true westward distance to Japan is in fact roughly 10,600 nautical miles. The actual distance from the Canaries to the Caribbean, where Columbus landed, is about 3,400 nautical miles. Ptolemy’s error was central to Columbus’s plan, and it is one reason why he was so surprised to find the Americas in the way.

The Islamic and Chinese Traditions

European cartography of the fifteenth century did not develop in isolation. The Islamic world had produced a rich tradition of geographic science: the Tabula Rogeriana of al-Idrisi, drawn in 1154 for the Norman king Roger II of Sicily, was the most ambitious medieval world map and depicted the inhabited world on a south-up orientation with remarkable care. Al-Biruni, working in the eleventh century, had developed sophisticated methods for measuring latitude and longitude. Arabic sailing directions and portolan-style charts of the Indian Ocean were the working documents of the Arab and Persian maritime trade.

Chinese cartography was also developed in the thirteenth and fourteenth centuries, and the magnetic compass, as we have seen, came to Europe from China. The deep history of mapmaking in Eurasia is a reminder that the European cartographic revolution of the Renaissance drew on a global inheritance. The argument of the historian of science David Woodward, in the second volume of the History of Cartography, is that the European cartographic revolution was distinctively European in its ambition to construct a complete, mathematically rigorous, and empirically updated world map — but the techniques and the data on which it drew were global.

The Portolan Tradition

The portolan chart was the working chart of pilots in the late medieval Mediterranean and Atlantic. The earliest surviving examples date from the late thirteenth century, and the tradition flourished in Italy (especially Genoa, Venice, and Pisa), Catalonia, Portugal, and France through the sixteenth century. The name “portolan” derives from the Italian portolano, meaning a collection of sailing directions, and the charts were typically accompanied by written sailing directions.

Portolan charts depicted the Mediterranean and the Atlantic coast of Europe with remarkable accuracy, often to within a few nautical miles of modern positions. The accuracy was based on the practical experience of pilots and on the cumulative corrections of many generations of navigators. The interior of continents was either left blank or filled with decorative and symbolic information, but the coasts were drawn with great care. The charts were crisscrossed by a network of rhumb lines, or loxodromes, radiating from sixteen or thirty-two compass points, and the rhumb lines allowed a navigator to lay a course from any point on the chart to any other by simply drawing a straight line and reading off the compass bearing. Combined with the mariner’s compass, this was a powerful and practical system.

The portolan tradition declined in the late sixteenth and early seventeenth centuries as the Mercator projection came to dominate marine cartography, but the empirical accuracy of the portolans was the foundation on which the great world maps of the Renaissance were eventually built. The transition from portolans to Mercator charts is treated on our portolan charts and piloting cluster page.

The First Modern World Maps: Behaim, Cantino, and Waldseemüller

The generation of cartographers active around 1500 produced the first modern world maps, drawing on the flood of new information from the Spanish and Portuguese voyages.

The Erdapfel of Martin Behaim (1492) was a globe, not a flat map, and is the oldest surviving terrestrial globe. Made in Nuremberg just before Columbus’s first voyage, it shows the world as Europeans understood it on the eve of the discoveries. The Atlantic Ocean shows as a relatively narrow body of water separating Europe from a large Asia, and the Americas are entirely absent.

The Cantino Planisphere of 1502 was a Portuguese world map that has been called the first modern world map. It depicts the African coast in detail, shows the line of the Treaty of Tordesillas, and includes the coast of Brazil, the Indian Ocean, and the Asian mainland. It reflects the new geographic knowledge generated by Vasco da Gama’s voyage to India in 1498 and by Portuguese exploration of the Brazilian coast.

The Universalis Cosmographia of Martin Waldseemüller, printed in 1507, is among the most celebrated documents in the history of cartography. It is the first map to depict the Americas as a separate continent and the first to apply the name “America” — honoring the Florentine navigator Amerigo Vespucci — to the New World. The map is based on Waldseemüller’s reading of Vespucci’s accounts of his voyages, and it reflects the rapid shift in European geographic understanding between 1492 and 1507. The Waldseemüller map is sometimes called the “birth certificate of America,” and it is the source of the name by which the continents have been known ever since.

The Mercator Projection

In 1569, the Flemish cartographer Gerardus Mercator published a large world map on what became known as the Mercator projection. The Mercator projection is a cylindrical projection designed specifically for marine navigation: a line of constant compass bearing (a rhumb line) appears as a straight line on the map. This property made the Mercator projection indispensable for navigators, and it became the standard projection for nautical charts from the seventeenth century onward.

The projection has a serious weakness that is often overstated. The Mercator projection distorts area at high latitudes, making Greenland look larger than Africa, when Africa is in fact fourteen times larger. The distortion was known to Mercator and was not a hidden flaw — it was a deliberate choice to preserve the navigational property. As a general-purpose world map, the Mercator projection has been largely replaced by the Robinson, Winkel Tripel, and other equal-area or compromise projections in the twentieth and twenty-first centuries. As a marine chart, it remains in use because no other projection has yet matched its navigational property.

Mercator’s contribution was not only the projection but the systematic mapping of the world on a uniform grid of latitude and longitude, the publication of accurate regional maps, and the development of a market for printed maps. His son Rumold and his collaborators continued the work after Mercator’s death in 1594, and the Mercator atlas became the standard reference for European cartography in the seventeenth century. The projection is treated in the broader context of navigation on our portolan charts and piloting cluster page.

Ortelius and the First Atlas

In 1570, the Flemish cartographer Abraham Ortelius published the Theatrum Orbis Terrarum (“Theater of the World”), generally considered the first modern atlas. The Theatrum was a systematic collection of maps of all the known regions of the world, drawn to a uniform format and accompanied by descriptive text. It went through dozens of editions in multiple languages and became the standard reference for European geographical knowledge in the late sixteenth and seventeenth centuries. Ortelius and Mercator were close collaborators, and their work together laid the foundation for the Dutch Golden Age of cartography in the seventeenth century, when Amsterdam became the center of the European map trade.

The Dutch Golden Age

The seventeenth century saw a flowering of Dutch cartography, centered on Amsterdam and the other great Dutch commercial cities. The Dutch East India Company (VOC), founded in 1602, was a major patron of cartographic work, funding expeditions to chart the East Indies, Africa, and the Pacific. The great cartographers of the period — Jodocus Hondius, Willem Blaeu, Jan Blaeu, Nicolaes Witsen, and many others — produced atlases, sea charts, and globes of remarkable accuracy and beauty. Dutch cartography was closely tied to Dutch maritime power, and the maps of the period reflect the global reach of the Dutch colonial empire. For a discussion of the accuracy of these maps and the earlier Renaissance maps on which they were based, see our page on how accurate Renaissance maps were.

Cartography and Empire

The making of maps was a strategic activity of European empires. Portuguese, Spanish, English, French, and Dutch authorities all maintained offices of cartography, hydrography, and navigation, and they often treated maps as state secrets. The Portuguese Casa da Mina e Índia and the Spanish Casa de Contratación in Seville were centers of cartographic activity, producing official charts of the new discoveries. The English, French, and Dutch hydrographic offices followed in the seventeenth and eighteenth centuries. Maps were instruments of empire, and they were often used to support territorial claims, to plan naval operations, and to direct commercial activity.

The Legacy

The cartographers of the Age of Exploration did more than draw pictures of the world. They created the visual language through which Europeans, and eventually the whole world, came to understand the Earth. The conventions of north-up, east-right maps; the idea of a complete world map showing all continents; the coordinate system of latitude and longitude; the projection of a spherical Earth onto a flat surface — all of these are products of the Renaissance cartographic revolution. The legacy of Ptolemy, al-Idrisi, Fra Mauro, Waldseemüller, Mercator, and Ortelius is the very framework of modern geographic thought.