There have been lots of attempts to create domed cities on a very small scale. Consider these examples:
- The Mall of America near Minneapolis is a tiny city under glass. It contains about 80 acres of floor space (on 27 acres of ground) holding more than 500 stores, 80 restaurants and an indoor amusement park.
- Biosphere 2 is a giant, completely sealed lab covering 3.15 acres.
- The two Eden greenhouses in England are geodesic domes that together cover about 5 acres.
- Any dome stadium covers eight to 10 acres.
What if we were to expand on these projects in a massive way, moving up to city-size and covering somewhere on the order of 650 acres -- approximately a square mile? We're talking about taking a square parcel of land measuring approximately one mile on each side, or a circular piece of land measuring 1.13 miles in diameter, and completely covering it.
The first question is what technology would we use to cover such a huge space. Here are three possibilities:
- The Mall of America uses typical mall construction technologies -- concrete and block walls, trusses, skylights, and so on. It's not very glamorous or inspiring architecture (there would be lots of supporting posts and walls in the city, rather than the dazzle of a mile-wide dome), but it is easy to imagine a construction process using these same techniques to cover a square mile.
- The Eden project uses a geodesic dome and hexagonal panels covered with multiple, inflatable layers of a very light plastic foil. The weight of the geodesic frame plus the hexagonal panels is about equal to the weight of the air contained inside the dome.
- The British Columbia Place Stadium is covered with a Teflon-coated fiberglass fabric held up by air pressure. The air pressure inside is only 0.03 psi higher than normal atmospheric pressure. Sixteen 100-horsepower fans provide the extra pressure.
In a project like covering a city with a dome, it may be that buildings form part of the structure for the dome. For example, six tall buildings at the center of the city could act as six pillars supporting the dome's center, with other buildings throughout the city acting as shorter pillars.