It's Curious City, where we take your questions about Chicago and the region, and investigate, report, explore, from WBEZ.

Sophia Madden grew up in Minneapolis.

And Chicago was the main big city that my family would visit on vacation.

She remembers long, boring seven-hour drives when she was a kid, and then seeing Chicago

skyline with the John Hancock Center looming over it.

And that was the dominating force and the surge of excitement that my brothers and I would

feel, knowing that we were so close to the

city. Her family stayed near the Hancock. They shopped nearby at the Lego and American Girl

stores. They usually made it to the top for the view. But she never knew too much about the building

itself. My question was, why is the John Hancock building so important to Chicago's history?

Well, Sophia, the John Hancock building so important to Chicago's history? Well, Sophia, the John Hancock Center, now officially known as 875 North Michigan,

but whatever, the John Hancock Center isn't merely important to Chicago.

It's important to city skylines across the world.

When it was completed 50 years ago, it totally changed what architects thought was possible.

It's got a great story featuring two young immigrants, architect Bruce Graham, originally from Columbia,

and a visionary structural engineer from Bangladesh, Fasler Khan.

But before we get to them, a little about the architecture in cities before the John Hancock Center.

The early 20th century had been a boom time for skyscrapers.

Every few years, a new world's tallest building would go up, culminating in the Empire State Building at 102 stories in 1931. And then the boom stopped, partly because

of the Great Depression in World War II, and another reason. So there was conventional wisdom

that said buildings as tall as the Empire State Building weren't really feasible or weren't really economic anymore.

This is Thomas Leslie, professor of architecture at Iowa State University.

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