What superstructures can you dream up?

The geek in me has always been fascinated by superstuctures like man-made islands and the Burj Dubai. I’m always awed at the thought that mere human beings can conceive of such things and make them real through applied technology and sheer, staggering bloody-minded hard work. Some of my favourite ideas though still lie just beyond the realms of possibility, like the “Lily-Pad” floating man-made floating island (see here), viable arcologies and mile-high buildings.

So if you were unrestrained by the limits of current technology, what sorts of superstructures could you dream up and what would you like to see become reality?

The space elevator is my enduring dream. Especially if there’s a couple of them across the globe and they’re connected at the top by a planet-encircling ring.

I have always been fascinated by Old Man River City. To be honest, this would be the perfect time for Detroit to scrounge funding and tear down the empty area, build it and move everybody into it and get rid of the rest of Old Detroit.

Think how much the city would save in infrastructure cost, mass transit, school systems. No urban sprawl, everything localized, everything brand new and up to code. The now emptied lands could have landscaping around the industrial sites, or a few brand new purpose built industrial sites constructed and the industries moved to them.

I’ve been wondering if a high-altitude elevator is possible now. A large enough lighter than air balloon that could be tethered to the ground with an elevator running on the tether. There has to be some current maximum height for which a ballon and tether can be practically made.

Luna City. Complete with giant mass driver to hurl wheat ferries to Earth.

A dyson sphere. Loved the idea ever since I saw it on Star Trek: TNG as a kid.

Other than that, something like SimCity 2000’s highest populated arcology. Kind of a giant self-contained building with trees and gardens up on top, and miles of corridors inside

When are we going to see some underwater domed cities?

I think we should basically turn the first couple thousand of feet below the lunar surface into millions of square miles of living space. All the excavated material could be moved to the surface to build living space upward a moon-spanning construction of even more millions of square miles of living space. The left over material could then be lifted off the surface and out to the two adjacent Lagrange points to construct Luna size satellites in those orbits.

As soon as you make the rank of Captain.

Some guy had the idea for something called Global Cassus. It’s sort of a Dyson Sphere Light where I guess we would take the Earth and turn it inside out like a giant orange peel.

As far as megastructures go, people have already thought of:
city domes
mile-high+ skyscrapers
supercorridors (half-mile wide multi-modal megahighways)
excessively large bridges or dams
arcologies (giant multi-use hive buildings)
man made island cities
sea domes
space elevators / skyhooks
ecumenopolis (Coroscant-like city planets)
Stanford torus (rotating ring space stations)
Bernal spheres (another space station design)
O’Neill cylinders (Babylon 5-like space habitats)
Oribital rings (like a man-made Saturn ring around the Earth)
the Global Cassus thing
Dyson spheres
Matrioshka brain (bunch of Dyson spheres inside each other)