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 theres a maths proof.

News stories about the concave building:
www.dailymail.co.uk/news/article-2786723/London-skyscraper-Walkie-Talkie-melted-cars-reflecting-sunlight-fitted-shading.html
www.bbc.co.uk/news/uk-england-london-23930675
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:
festivalofthespokennerd.com/

Play with the Geogebra parabola demonstration:
www.geogebra.org/material/show/id/189498

Music by Howard Carter
Design by Simon Wright

MATT PARKER: Stand-up Mathematician
Website: standupmaths.com/
Book: makeanddo4D.com/
Nerdy maths toys: mathsgear.co.uk/