The building in London at 20 Fenchurch Street started to set things on fire! But it could have been worse. I use a paraboloid to set other things on fire. Oh, and there's a maths proof. News stories about the concave building: http://www.dailymail.co.uk/news/article-2786723/London-skyscraper-Walkie-Talkie-melted-cars-reflecting-sunlight-fitted-shading.html http://www.bbc.co.uk/news/uk-england-london-23930675 http://www.independent.co.uk/news/uk/home-news/walkie-talkie-skyscraper-to-be-fitted-with-permanent-sunshade-after-it-melted-cars-9379037.html Festival of the Spoken Nerd: http://festivalofthespokennerd.com/ Play with the Geogebra parabola demonstration: http://www.geogebra.org/material/show/id/189498 Music by Howard Carter Design by Simon Wright MATT PARKER: Stand-up Mathematician Website: http://standupmaths.com/ Book: http://makeanddo4D.com/ Nerdy maths toys: http://mathsgear.co.uk/