The tower at 20 Fenchurch Street (nick-named the Walkie-Talkie) dominates the skyline when looking towards the City from the Thames due to its distinctive shape and with it being a little away from the rest of the cluster of City towers. In the summer of 2013 the concave shape of the tower's south aspect along with the extent of glass caused it to act as a parabolic mirror, directing the sun's rays onto nearby streets, and, in one case causing the front wing of a Jaguar car to melt and deform. The black sheeting visible on the tower is presumably an attempt to stop this happening before a more elegant solution is found. As well as being known as the "Walkie-Talkie", the mirror effect means it is also now known as the "Fryscraper".

http://en.wikipedia.org/wiki/20_Fenchurch_Street
http://www.bbc.co.uk/news/uk-england-london-23930675