You've forgotten the Perchlorates. OTOH the atmosphere of Venus at a certain height is allegedly not so hellish, and would enable free-floating platforms up to

You've forgotten the Perchlorates. OTOH the atmosphere of Venus at a certain height is allegedly not so hellish, and would enable free-floating platforms up to city-size due to buyoancy of normal earth atmosphere at that height. Not that much sulphuric acid up there either, managable by already common and mass-produced materials. Also even moar solar! And endless carbon-supplies to suck up. Call it Bespin, Cloud9, whatever...