One hundred years ago, Einstein's theory of general relativity was announced to the world. Our concepts of black holes, time travel, and the Big Bang beginning of our universe are all consequences of Einstein's great theory. To celebrate, this program visits three 'big physics' facilities: CERN's Large Hadron Collider in Switzerland, the vast dark matter laboratories under a mountain in Italy; and two three-kilometre rooms where scientists are hoping to prove a prediction Einstein made over a century ago – that gravitational waves exist.