New York City's Central Park can feel like an untouched slice of nature in the heart of Manhattan, but every square foot of the 843-acre park was carefully planned and constructed. When New York legislators approved construction of a massive urban park in 1853—the first of its kind in the United States—they chose some of the least attractive land in the city. "It was junk land," says Cynthia Brenwall, a conservator at the New York Municipal Archives. "It was not nice, beautiful and hilly like it is now. It was rocky and full of bogs. There were gross tanneries and bone-boiling plants. It was attractive because it was easily attainable."

The transformation of "junk land" into one of the most-visited and beloved parks in the world required one of the largest public works projects in 19th-century America. From 1857 to 1866, more than 20,000 labourers armed with pickaxes, carts and gunpowder removed and reworked nearly 7 million cubic feet of rock and soil to shape Central Park into the verdant work of public art it is today.

From 1840 to 1850, the population of New York City grew from 327,000 to almost 600,000. The vast majority of New Yorkers still lived in the southern tip of Manhattan, but city planners predicted the growing metropolis would soon cover the whole island. If New York was going to be a world-class city at par with Paris and London, it needed an open green space like the Tuileries Garden or Hyde Park where residents could escape the noise and pollution of city life. "Poor New Yorkers who lived in tenements weren't going out into the country on the weekends," says Brenwall, author of The Central Park: Original Designs for New York's Greatest Treasure. "They didn't summer in the Hamptons. They worked six days a week and had one day to recuperate. Central Park was supposed to be a way to be out in the 'country' without leaving the city."