Only four days to go until the start of the London 2012 Olympic Games! To get into the spirit, we cast our minds back to one of our favourite features of the 2008 Beijing Games: the beautiful aquatics venue, known as the *water cube*. Looking like it's been sliced from a giant bubble foam, the design is based on an unsolved maths problem. And although the bubbles look completely random, the underlying structure is highly regular and buildable. Find out more about this beautiful building in our article Swimming in mathematics.

The Water Cube at night. Image © Chris Bosse.