The big tube near Nottingham? The biggest one? You could fit ROME, as a CITY down that!! (Rome being a size 1 city I nuked to oblivion, before finding out that invisible units can't capture cities
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The actual Arcology, if extended to real life (assuming the two planets are approximatly equal sized), would be able to fit France, Belgium, Netherlands, Germany, Northern Italy, Switzerland, Austria, the Czech Republic, Poland, Slovakia, Hungary, and Slovenia, under it's immense size. The actual diameter of such a monstrosity is 1,000 kilometers. This means that, not only would it be visible in space, but, if it was hemispherical, then the dome would look like a GIANT growth on the Earth, being 1/12th of the diameter of the earth!. The dome, if made a perfect sphere, would be 1/3rds of the diameter of the moon (or, 1/27th of the volume). The big metal thing near Nottingham would be the size of Switzerland, and just over a third of it, would technically be in space. Assuming a (liberal) size of 100km X 50km X 150km, and an average density of around 1/2 of steel (Half of it being steel, and the other half, tubes of air of neglible weight), and assuming the steels density is the (lower) 7500 kg/m^3, the metal box ALONE would weigh 2.8 MILLION BILLION tons. Approximatly.
The actual game took me ages, 26 hours, and 1 minute, spread over the course of 2 weeks. And I plan to do another one very soon ^.^ There were 3 major nuclear battles (Spain nuking the entire Siamese east coast, with the 10 tactical nukes I gifted. That radioactive pile wasn't sorted fast enough, and it quickly revolted, first as the Aztecs, then as the Americans; followed by the Abyssinia vs. Rome, where some 40+ nukes found Roman soil. Only 5 nukes were returned; and finally, me vs. a mean-looking mountain, where I fired 10 nukes at a harmless mountain to re-start global warming. Unfortunatly, it never happened
I had only about 20~30 tiles of mine turn to desert, and with my Soylent Green factories pulling 70% of the food production as my farms, and cereal mills giving me 24
at it's peak, as well as +24% food, I wasn't scared of my entire empire turning to desert...
If you can think of a better caption, please tell me. I suck at captioning