Few books in history have affected the development of mathematical, scientific, and philosophical thought more than Euclid's Elements. The propositions and figures in the first 4 books form the geometric core of the work. We have turned the 127 original black and white static figures into colorful, interactive apps that illustrate the propositions dynamically. What translator Sir Thomas Heath calls "one of the noblest moments of antiquity" is newly dressed for the 21st century, made possible by Geometry Expressions software from Saltire Software.