Zip Line Tours Through City Space

[Image: Photo by Ryan Collerd for The New York Times].

Riding zip lines through the autumn tree canopies of rural Pennsylvania is something of a growth industry, it seems, exploring ski resorts during the off-season by speeding downhill at 50 mph in a roped-up harness.
From The New York Times:

Some zip lines are basically thrill rides that follow the cut of ski slopes and at this time of year offer expansive views of the autumn blaze of colors, along with an adrenaline rush.

Other courses (like the one we were on) are marketed as canopy tours, designed with a challenging combination of swaying sky bridges, cable traverses and zip line pathways cut through the deep forest. Once we climbed a cargo net to reach our first tree platform, we were literally amid the autumn foliage, not quite in the canopy of fully grown oaks and poplars but close enough to squirrels to guess their sex as they scampered from limb to limb just above us.

This kind of vertical immersion in an otherwise inaccessible overhead landscape is incredibly interesting, in and of itself – but 1) it also reminds me of a 2007 project by artists Steve Lambert and Packard Jennings in which they reimagined the city of San Francisco as a city of roller coasters, wildlife preserves, underground libraries and health clubs installed inside BART cars, and, of course, zip lines across the San Francisco Bay.

[Image: Riding zip lines to Oakland; by Steve Lambert and Packard Jennings].

And 2) the two of these together seem to imply a new kind of urban tourism, where you don't talk guided walks or buy tickets for double-decker buses: you ride zip lines above Notre-Dame cathedral and down Fifth Avenue, getting up close and personal with architectural ornament at a level of detail you would otherwise never have seen.
Sky Tours of Manhattan.
In the same way that you can take, for instance, Entourage-themed bus tours of Los Angeles, you could take Spiderman-themed zip line tours of New York.
You call up Canopy Tours and ask them to price-out the entirety of Chicago. Or Istanbul. (At the very least, they could map it).
Zip lines through the London financial district.
Zip lines through the sandstone arches of Utah.
Zip lines through Angkor Wat.
A Zip Line Olympiad across the domes and spires of central Europe.
Or don't use zip lines for humans at all; attach plants to them for the hanging zip line gardens of the 21st century. Flowering plants and ferns and oak trees go whizzing by in an aerial gardenry that defies belief.
And if zip lines could realistically open up a whole new world of spatial volume in the modern high-rise metropolis, what new architectures and city surfaces might result?