Step into the new Tilt! attraction on the 94th floor of the John Hancock Center and at first nothing happens.
You are holding big metal bars. You are peering through a full-length window. But you know what is about to occur, and your insides, you are not ashamed to say, are like a crowded butterfly garden.
And then there's a sound - think noisy dentist's office, or airplane engine at the gate - and the eight-window chunk of wall you are clinging to begins to quit its right-angle orientation to the massive skyscraper around it.
You and the wall and the other fools at the other windows are pitched slowly forward, and you begin to think about your mortality and America's long legacy of engineering successes.
You think about the city elevator inspectors who evaluated this thing, and you wish that one of them were here alongside you, his presence the most reassuring safety certificate of all. You think, for some reason, about your sofa back home, comfy, welcoming, earthbound.
Once upon a time in tourism, a commanding view from way on high was attraction enough. But recent years have seen an escalation in the race to induce vertigo.
Operators at the Grand Canyon and the Willis Tower have installed glass overhangs so that visitors can step out past precipices. And now there is Tilt!, officially open to the public and billed as unique in the world. You, really, are in no position to argue.
At 20 degrees from vertical, your body tells you it should be falling. Looking down, you see your presumptive target: Chestnut Street, or, with the right wind and a bit of a leap and a soar, the top of the Water Tower Place building across the street. Welcome, shoppers. Your knuckles match the white in the nearby clouds.
This feeling, you imagine, is why it is better to watch the rooftop chase scenes at the beginning of James Bond movies than to participate in them.
At 30 degrees, the full extension of Tilt!, you could let go and become a giant bug on a giant windshield, except that, unlike such bugs, you would remain sensate. Also, you are on the inside. As the mechanism pauses to let you take it all in, you are slowly acclimating to this challenge to your equilibrium.
Where once you thought "yikes" or "zounds" - or whatever combination of "holy" and "(bad word)" you use to express wide-eyed amazement tinged with fear - now you are beginning to take in the city that spreads beneath you: the actual Water Tower that survived the Great Chicago Fire, Michigan Avenue, the park behind the Museum of Contemporary Art.
This view, as you are pitched forward like the figurehead on the prow of a ship, extended out over 1,000 vertical feet of air, is breathtaking. It could be the fresh perspective on familiar places stealing your wind, but it is more likely the result of your lizard brain telling you your body, right now, is supposed to be plunging into those known locales.
But your human brain is winning the argument. This is safe. This is well-thought-out, by people who know how wind, metal, glass and hydraulics behave. This is, really, very cool.
With Tilt!, 360 Chicago, the new name for the old John Hancock Observatory, makes a bold move toward being better at putting metaphorical lumps in tourists' throats than any other place in town. (Pizzeria Uno holds the title for physical lump placement.)
There's the Ferris wheel at Navy Pier, combining vintage charm with modern height. There's the Ledge, the single name for the four glass boxes that jut four feet out from the western wall of Skydeck at the Willis Tower, still a potent threshold to cross, almost five years after it opened.
But Tilt! does something new, something I found entirely enchanting. It moves you. It nudges you forward, then pauses, then tilts you forward some more. It puts your life in the hands of a machine, and it makes a substantial thing - the majestic, cross-braced Hancock tower - suddenly whimsical.
But if a window wall rotating outward is playful, there is nothing light about the way it is built. It is a box of steel, 14,061 kilograms of it, powered by a hydraulic motor and three big pistons known as hydraulic actuators.
Just as the Hancock wears its support pieces like a bandit's guns, on the outside, visitors to Tilt! can see the giant nuts and bolts and the heavy beams doing the work of keeping them safe; they can touch a glass panel that shows what the three-layer, tempered, laminated structural glass used in the windows is like.
Designers at Willis' Skydeck Ledge seemed to want to invite people to walk out into the air. Although the Willis structures, too, are movable boxes anchored within the boundary of the building, the part that juts out, that you walk out onto, seems to challenge you to find the support pieces. In these terrariums for the trusting, there's an illusion of danger.
Tilt!, on the other hand, wears its engineering on its sleeve, coming across as a more mechanised thing, as, dare we say it, a slow-motion thrill ride.
Apparently, we do not dare. "We tend not to use the 'R' word. We call it an 'experience,'" said Jennifer Hesser, 360 Chicago's director of operations and one of the people who guided the Tribune and NBC's "Today Show" through the first media experiences, Wednesday morning.
There was a ribbon-cutting Thursday morning, after which, word has it, members of the public would be able to start tilting even in advance of the official opening Saturday.
The experience lasts maybe 5 minutes in the Tilt! area along the observatory's south wall, and 75 or so seconds in the mechanism itself. The charge is US$5 (NZ$5.8) extra atop standard 360 entrance fees of US$18 for adults, US$12 for children 3-11. (The US$5 is an introductory rate; to be determined are how long it will last and what the normal charge will be.)
Officials at 360 Chicago, purchased by the French attraction operator Montparnasse 56 in 2012, said Tilt! is not a direct response to Willis introducing the Ledge. But, come on. Planning began "a few" years ago, with work "in earnest" starting about 18 months ago, said Nichole Williamson, 360 Chicago's general manager.
"There was a desire to try to create an interactive way to experience the views," said Williamson. "Our position is that having two observation decks in two iconic buildings with two different experiences speaks to the city's character of innovation."
And having Tilt! in 360 Chicago means tourists are more likely to visit there, rather than go to the Signature Lounge one floor above and look at the views from that establishment for the price of a cocktail.
Shortly before lunchtime on Wednesday, representatives from the Chicago office of the big engineering company Thornton Tomasetti also came by for an advance look at Tilt! - fitting because their firm had designed it.
"So is it a little better than the mock-up?" asked John Peronto, one of the structural engineers who worked closely on the project, as a group of his colleagues tried out Tilt!, some facing forward and streetward, some leaning back against the glass to look up at the top of the Hancock.
"It's almost like we were designing a piece of construction equipment that we were putting into place," said Christian DeFazio, another of the Thornton Tomasetti engineers on the project. "It was not a textbook scenario, by any means. When you are literally putting people outside the building, there's an extra fear factor in your design."
And DeFazio should know because, well, "I'm terrified of heights," he said.
Yet when he first tried Tilt! - built at TrussWorks International in Anaheim, California. - "I felt confident getting into it," said DeFazio. "I knew I was in good hands."
It took me a little longer. At first, everything seemed wrong and dangerous, and my moves were tentative, ginger, even though I knew, intellectually, that nothing I could do would make one whit of difference.
By the end of an hour of seeing it in operation, I was jumping in and out of the bays. Still, I was grateful that they hadn't decided to call this non-ride, say, Tilt-a-Whirl! Just plain tilting was plenty.
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