The first survey of a nation to use modern trigonometric methods began in late seventeenth-century thanks to France’s King Louis XIV’s royal astronomer, Giovanni Cassini. The next three generations of Cassinis spent years labouring over the creation of the Carte de France, a vast, 182-sheet map of the country on a scale of 1:86,400 which, if joined together, would cover twelve metres high and eleven wide. Teams of trained surveyors crisscrossed France, measuring every square meter (a unit of measurement adopted by France in 1793, thanks largely to the Cassinis’ efforts). Some were attacked, one even murdered by suspicious locals, but their heroic efforts led to some of the most accurate and beautifully engraved maps in the history of cartography. The survey was nearly completed when France was engulfed by revolution in the 1780s. One of the new republican regime’s first decisions was to nationalize the map, shown here in Louis Capitaine’s composite version. Its methods were to set the standard for all subsequent national mapping surveys.