The interesting thing about that is, the first globe (the Erdapfel) wasn't (reportedly) made until 1492.
I'm having a hard time figuring out why the inhabitants of a planet would wait 1800 years (assuming 275 BC was when they were "aware" their world was a ball) to create a model of their world, if they truly knew the shape. One thing is for certain though, they sure were creating a lot of flat maps during that time. ;)