... The Round Earth . ... When Christopher Columbus proposed to reach India by sailing west from Spain, he too knew that the Earth was round. ... The Alexandria philosopher Eratosthenes went one step further and actually estimated how large the Earth was. ... Eratosthenes himself lived in Alexandria, near the river's mouth, north of Syene, about 5000 stadia north of Syene (the stadium, the size of a sports arena, was a unit of distance used by the Greeks). ... Questions from Users: Why is the Earth...