Massimo De Martini's face assumes a look of concentrated pleasure as he slips the delicate sheet of paper, 16in by 27in, from its protective plastic sleeve.
He spreads the page carefully across a leather bureau top. It's a map of the world, printed in Florence in 1482. It smells musty, with a citrus top note, and it will be one of the star attractions at the London Map Fair. It would set you back about £120,000. Mr De Martini says he's open to negotiation.
We now know vastly more about the world than Abraham Ortelius, who etched and printed the world's first modern atlas – but the mystique, and value, of historic maps remains potent.
In 1570, an Ortelius atlas would have cost today's equivalent of £20,000, for in the 16th century maps were bought by royalty and the rich to measure empires and assess physical weak spots in rival lands and cities. Sotheby's recently sold an Ortelius atlas for £2.3m; and the US Library of Congress paid $10m for the first map of America, printed in 1507.
Historic maps remind us of the craft, science and sheer risk of exploration. In the 15th century, to pass through the straits of Gibraltar and sail due west, or to sail south from Ceylon, was to enter terra incognita – the absolute unknown.
Braun and Hogenberg's bird's-eye-view map of London must have seemed almost hallucinatory in 1547, long before even hot-air balloons. And to study Fra Mauro's world map from 1459 is to encounter the vivid surreality of early cartography and geography.
No wonder some collectors have been waiting 20 or 30 years for a particular map to come on to the market. "You catch the fever," says Mr De Martini cheerfully, carefully sliding the Florentine world map back into its protective plastic sleeve. "You don't have to spend thousands. You can buy a map more than 100 years old for £50 or £100. And as soon as you buy two maps – well, you're a collector! It's highly contagious."
Fortunately, the London Map Fair's historic atlases, travel books, globes, sea charts, town plans, celestial maps, topographical prints and reference books will be antidotes for even advanced cases of cartomania.
London Map Fair: June 11&12, Royal Geographical Society, 1 Kensington Gore, London.
Maps that changed the world
Reconstructed world map by Pomponius Mela
Pomponius was the first Roman geographer and, in the 1st century AD, mapped the world as five zones: frozen in the north and south, and a torrid central band with habitable strips above and below. Like earlier Persians, he showed the Caspian Sea as an inlet of the so-called Northern Ocean.
Gerardus Mercator, 1512-94
The Flemish cartographer created the first realistic and accurate world map, minimising the overstretched east-west effect on earlier maps based on cylindrical projections. His maps were the key breakthrough in nautical cartography, and Mercator map projections are still the most commonly used today.
Ptolemy's world map, 150AD
The Greek astronomer's 150AD treatise, 'Geographia', contained the first mapping calculations made using celestial observations, perspective projections and grids. His revolutionary calculations created the concept of global mapping coordinates. The first modern copy of the Geographia was produced in Bologna in 1477.
Bode Celestial Atlas, 1801
Johann Bode's 'Uranographia' comprised the first accurately scaled maps of thepositions of planets, stars, and artistically presented constellations. Bode, who was director of the Berlin Observatory, also identified and mapped the orbit of Uranus, which he named. Bode's atlas led to improved nautical navigation.
Fra Mauro's Map, circa 1450
Made by a Venetian monk, this Mappa Mundi, or cloth of the world, is considerably more beautiful than the much earlier Hereford Mappa Mundi. Medieval maps, like earlier Babylonian "symbolic" maps, were not just speculations about land masses: they illustrated wider subject matter such as mythology and "exotic" races.
Theatrum Orbis Terrarum, 1570
Abraham Ortelius's masterwork, published in Antwerp, was the first modern atlas. This single book triggered a stampede of atlas and map publishing that spread through Italy, Germany and France, creating a market for maps as repositories of increasingly accurate data of great commercial, strategic, and political significance.
The Kitab-i Bahriye, 1513
The Ottoman cartographer Piri Reis published navigational maps in his Kitab-i Bahriye, which contained charts and sailing instructions covering segments of the Mediterranean. A later edition included a map of the Americas, although the first depiction, in 1500, was by Juan de la Costa, a conquistador who sailed with Columbus.
The 13th century replica of the original 5th century map is set out on a 6.75m- long parchment scroll and shows the network of roads in the Roman empire, covering key routes in Europe, Persia and India. The parchment, which is frail and never exposed to bright light, has been placed on UNESCO's Memory of the World Register.