Question

Over two thousand years ago the diameter of the earth is known to have been measured where?

Answer 1

Earth's circumference was first accurately measured more than 2,000 years ago by the Greek astronomer Eratosthenes, who at the time lived in the Egyptian city of Alexandria. He had heard that in the nearby town of Syene midday sunlight shines straight down to the bottom of deep wells on the same day each year, indicating that the Sun was directly overhead in Syene. In Alexandria, however, sunlight on that date never reached the bottoms of wells, but instead fell upon the sides.