Archimedes of Syracuse
Archimedes was born in 287 BCE in Syracuse on Sicily, then a Greek city-state. The son of an astronomer, he was a brilliant mathematician, engineer, astronomer, physicist, and inventor. Perhaps his greatest mathematical contribution was his calculation of an upper limit to pi. This lasted until the late twentieth century, when electronic calculators came into play and made even more precise calculations possible. He also discovered and proved formulae for the surface area and volume of spheres. He was a pioneer in applying mathematics to the physical world.
It was he who, struck by an insight, was said to have leapt from his bath and run down the street naked yelling "Eureka, I've found it!"