There is a support tower close to each end of the route, but between those points the two cars – which look like a cross between a viewing platform and a hovercraft – hang from 2km of cables, which because of their weight droop down towards the valley floor.
We all stand on a viewing platform and watch as four graceful wolves trot into view.
The first is a 660-metric-ton ball installed between the 87th and 91st floors and observable from public viewing platforms on the 88th and 89th floors.
"We were on the viewing platform earlier and could see them coming up.
Preferred viewing platforms included beaches, boats, fields and hot air balloons.
From wooden viewing platforms we spot massive-hootered toco toucans and shy red brocket deer.
Diller and Scofidio have already completed two viewing platforms this year.
There is no jostling, crowded though the viewing platforms are, little litter, no yelling, no tussles between young men.
Then the ground level sloped and twisted along a low-ceilinged pathway dotted with viewing platforms.
