What a man can do on Niagara.
How easy would it be to push a blindfolded man off a tightrope? Not easy at all, if the man's name is Nik Wallenda. To get in practise for the 120mph gusts of wind he faces when walking a wire several hundred feet in the air, the daredevil gets family members to try and make him lose his balance.
"They push me harder and harder and I'll stay on the wire. Never come off. Never," says Wallenda who will be performing his latest stunt this coming Sunday, November 2.
After walking across Niagara Falls and the Grand Canyon, his next sky-walk will span three skyscrapers in Chicago.
The first stage will take him from the 578ft Marina City west tower, across the Chicago River to the 635ft Leo Burnett building - and it will be uphill all the way, with the tight wire rising at a 15-degree angle.
Then, he'll put on a blindfold and walk from the east Marina City tower to the west.
For a member of the world's most famous wire-walking family, he says risk is "just what we do."
What does it take to be a tightrope walker? I asked Alexa Leconte who skips, dances and lies on a wire - at albeit rather lower levels than Wallenda - in Spanish circus troupe Circ Panic. "A level head and a lot of muscle," she answers. Read her story, and those of trapeze artists, clowns, sword-swallowers, tiger trainers and showmen in Circus Mania - The Ultimate Book For Anyone who Dreamed of Running Away with the Circus.