[mainstreet]

It's strange - the John Hancock Center is so close to being another average 60s slap of black office space, but it's that very subtle decreasing width as it gets higher, the slightly diagonal sides, that makes it near genius. It happens to be a really, really great skyscraper, something rare for the 60s and 70s. It compliments Chicago's skyline really nicely too, I'm not sure it would work as well in, say, lower Manhattan, since Chicago seems to have just the right amount of space between skyscrapers for the Hancock Center, just the right density.