The Millenium Bridge. It was build, it wobbled, and was rebuilt. Now non-wobbly. See the Wikipedia entry for details. Surprisingly, the official website gives less prominence to the rebuild.
The Tate Modern - the most-visited modern art gallery in the world. You should try it.
Artist Melanie Smith is interviewed in her Mexico City studio for the TateShots podcast series.
Exploring Highwalk London
Copyright Jon Verrier, 2013