Having been to London numerous times, I have never had the chance to go and see the Thames Barrier. Thanks to my aunt, I got to see it on my recent trip! The Barrier was created between 1974 and 1982 in a bid to stop London from flooding with rising tidewaters. It's an amazing feat of engineering, and I think is rather pleasing aesthetically.
The shot below is HDR, actually processed from a single RAW file.
Close-up of a single tower with the Millenium Dome in the background: