I've been fascinating by mankinds works of structural engineering that have been created over the past few thousand years. One of my personal favourites is the artificially created palm tree-shaped islands in Dubai, they look beautiful:
http://www.yorkshireprofiles.co.uk/...ievements/ What's your favourite structure? Is it your favourite down to the amount of work and creativity that was put into it, or just simply because of how amazing it looks?