Knox and Vivienne Jolie-Pitt's Fourth Birthday

It was four years ago today that Angelina Jolie and Brad Pitt welcomed twins Knox and Vivienne at a hospital in Southern France. Their family instantly went from a six-some to a group of eight, but that didn't slow the Jolie-Pitts down. They've continued traveling around the world together, from the US to Malta and beyond — click through to see all of the exciting places Knox and Vivienne have traveled in their four years!