When a man-made disaster of unfathomable scope strikes your city and its central symbol of prosperity has been leveled to ruin — and it’s your job to jolt it into resurgence — where do you begin?

Only hours had passed after the planes struck New York City’s twin towers on Sept. 11, 2001, when then-Mayor Rudy Giuliani made a promise to rebuild: “We’re not only going to rebuild, we’re going to come out of this stronger than we were before.”

Four months later, New York’s new mayor, Michael Bloomberg, stood on the flag-clad steps of City Hall and echoed that promise: “We will rebuild, renew and remain the capital of the free world. … In the next four years I will devote myself to building a better New York.”

Days later, Bloomberg’s deputy mayor for economic development and rebuilding, Dan Doctoroff, assembled the heads of the city’s many agencies in one room. He made a big request: Each team was to produce a strategic plan and a timeline for the next year. Regular updates would be presented at what would become monthly meetings.

People were dumbfounded, Doctoroff says. Part of it was the how: “No one had ever done PowerPoint before,” he says. But also the what: “There was never that kind of level of City Hall-driven coordination on such a large scale.” It’s been decades since New York City had a citywide comprehensive planning vision.

How New York City Rebuilt Anew After Its Darkest Day

Photos: Spencer Platt/Getty Images, Mario Tama/Getty Images (2), Gary Hershorn/Getty Images