How did flat Earth conspiracy theory start?

Flat Earthers believe that the Earth is not spherical, but rather a flat disc and the Sun and the Moon are also flat discs that circle above the Earth. According to them the edges of the world are surrounded by a wall of ice, which is what we know as Antarctica. And as for the pictures of the Earth from space - they are all fake, part of a huge conspiracy to hide the truth. The earliest cultures that believed …