Oops - that line above should have read: "...shadows at different locations at the same time of DAY."

Another very common misconception is the belief that everyone at the time thought the world was flat and they were afraid of "falling off the edge".. People back then were less educated, but they were not stupid or blind. Even the ancient Greeks figured out that the world was round by measuring the length and direction of shadows at different locations at the same time of time. Also, anybody who watched a ship sail over the horizon could figure out that the earth had some curvature. The ancients and the medievals knew the earth was round, although they vastly under-calculated it's size.