How Leonardo da Vinci Drew an Accurate Satellite Map of an Italian City (1502)

When I look at maps from cen­turies ago, I won­der how they could have been of any use. Not only were they filled with mytho­log­i­cal mon­sters and mytho­log­i­cal places, but the per­spec­tives most­ly served an aes­thet­ic design rather than a prac­ti­cal one. Of course, accu­ra­cy was hard to come by with­out the many map­ping tools we take for granted—some of them just in their infan­cy dur­ing the Renais­sance, and many more that would have seemed like out­landish mag­ic to near­ly every­one in 15th cen­tu­ry Europe.

Every­one, it some­times seems, but Leonar­do da Vin­ci, who antic­i­pat­ed and some­times steered the direc­tion of futur­is­tic pub­lic works tech­nol­o­gy. None of his fly­ing machines worked, and he could hard­ly have seen images tak­en from out­er space. But he clear­ly saw the prob­lem with con­tem­po­rary maps. The neces­si­ty of fix­ing them led to a 1502 aer­i­al image of Imo­la, Italy, drawn almost as accu­rate­ly as if he had been peer­ing at the city through a Google satel­lite cam­era.

“Leonar­do,” says the nar­ra­tor of the Vox video above, “need­ed to show Imo­la as an ichno­graph­ic map,” a term coined by ancient Roman engi­neer Vit­ru­vius to describe ground plan-style car­tog­ra­phy. No streets or build­ings are obscured, as they are in the maps drawn from the oblique per­spec­tive of a hill­top or moun­tain. Leonar­do under­took the project while employed as Cesare Borgia’s mil­i­tary engi­neer. “He was charged with help­ing Bor­gia become more aware of the town’s lay­out.” For this visu­al aid turned car­to­graph­ic mar­vel, he drew from the same source that inspired the ele­gant Vit­ru­vian Man.

While the vision­ary Roman builder could imag­ine a god’s eye view, it took some­one with Leonardo’s extra­or­di­nary per­spi­cac­i­ty and skill to actu­al­ly draw one, in a star­tling­ly accu­rate way. Did he do it with grit and mox­ie? Did he astral project thou­sands of miles above the city? Was he in con­tact with ancient aliens? No, he used geom­e­try, and a com­pass, the same means and instru­ments that allowed ancient sci­en­tists like Eratos­thenes to cal­cu­late the cir­cum­fer­ence of the earth, to with­in 200 miles, over 2000 years ago.

Leonar­do prob­a­bly also used an instru­ment called a bus­so­la, a device that mea­sures degrees inside a circle—like the one that sur­rounds his city map. Painstak­ing­ly record­ing the angles of each turn and inter­sec­tion in the town and mea­sur­ing their dis­tance from each oth­er would have giv­en him the data he need­ed to recre­ate the city as seen from above, using the bus­so­la to main­tain prop­er scale. Oth­er meth­ods would have been involved, all of them com­mon­ly avail­able to sur­vey­ors, builders, city plan­ners, and car­tog­ra­phers at the time. Leonar­do trust­ed the math, even though he could nev­er ver­i­fy it, but like the best map­mak­ers, he also want­ed to make some­thing beau­ti­ful.

It may be dif­fi­cult for his­to­ri­ans to deter­mine which inac­cu­ra­cies are due to mis­cal­cu­la­tion and which to delib­er­ate dis­tor­tion for some artis­tic pur­pose. But license or mis­takes aside, Leonardo’s map remains an aston­ish­ing feat, mark­ing a seis­mic shift from the geog­ra­phy of “myth and per­cep­tion” to one of “infor­ma­tion, drawn plain­ly.” There’s no telling if the arche­typ­al Renais­sance man would have liked where this path led, but if he lived in the 21st cen­tu­ry, he’d already have his mind trained on ideas that antic­i­pate tech­nol­o­gy hun­dreds of years in our future.

Relat­ed Con­tent:

Carl Sagan Explains How the Ancient Greeks, Using Rea­son and Math, Fig­ured Out the Earth Isn’t Flat, Over 2,000 Years Ago

The Ele­gant Math­e­mat­ics of Vit­ru­vian Man, Leonar­do da Vinci’s Most Famous Draw­ing: An Ani­mat­ed Intro­duc­tion

Leonar­do da Vin­ci Saw the World Dif­fer­ent­ly… Thanks to an Eye Dis­or­der, Says a New Sci­en­tif­ic Study

Leonar­do da Vinci’s Ear­li­est Note­books Now Dig­i­tized and Made Free Online: Explore His Inge­nious Draw­ings, Dia­grams, Mir­ror Writ­ing & More

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness

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