Flat Earth
Fantasy fiction often imagines a flat Earth. In C. S. Lewis' The Voyage of the Dawn Treader the fictional world of Narnia is "round like a table" (i.e., flat), not "round like a ball", and the characters sail toward the edge of this world. Terry Pratchett's Strata and Discworld novels (1983 onwards) are set on a flat, disc-shaped world resting on the backs of four huge elephants which are in turn standing on the back of an enormous turtle.