This 1929 cover from an American speculative fiction magazine inspired Janey Cook to rebuild that fantastic sky city using Lego.
[Images: New air city by Janey Cook; photographs by Calum Tsang and Allan Bedford. Air Wonder Stories cover from Frank R. Paul's online gallery of sci-fi cover art. More covers coming up soon, in fact, because most of them are completely ridiculous – though architectural. Meanwhile, see the Lego Escher at gravestmor and, of course, The Brick Testament].
(Thanks to Peter Hoh for the link!)