loqu wrote:I know that in the Middle Ages they thought the Earth was flat, but what was it like in their times?
An educated Roman would absolutely know about the earth being round, and also be able to correctly explain such phenomena as lunar eclipses. And, contrary to what many believe, this view never ceased to be commonly accepted, even in medieval times. (This is amongst the educated, of course; if you had no experience of the world outside your own little town, you might of course have any or no conception about the form of the earth. But I think it is fair to say that, if you were able to read, you would have been, at the very very least, exposed to the idea of a spherical earth.)
See, for example, http://en.wikipedia.org/wiki/Myth_of_the_Flat_Earth
Edit: That is, there were never any real dissention concerning the spherical earth theory in the Middle Age; this should of course not be confused with two other related concept, about which there was a genuine debate, namely 1) whether or not humans could live on the other half of the earth, below the equator, and 2) whether the earth revolved around the sun, or vice versa.