Born in Alexandria c.325 BC, Euclid is most famous for his work entitled The Elements. Based upon only 5 postulates, Euclid developed the foundations of Geometry as every unfortunate high school student knows it. One of the more interesting things about Euclid's work is that it provided a basis for future groundbreaking mathematics. For instance, in the 19th century, mathematicians developed a field of mathematics called "Non-Euclidean Geometry." Using Euclid's work, they attempted to negate certain postulates and observe which of Euclid's theorems no longer applied and could be adapted to the new system. The most useful Non-Euclidean Geometry to come out of those studies was Hyperbolic Geometry, which is essentially Euclidean Geometry with lines replaced by curves. This geometry contributed heavily to further advancements in knowledge about space, time, and relativity. Euclid died in Alexandria c.265 BC.