The modern misconception that educated Europeans at the time of Columbus believed in a flat Earth, and that his voyages refuted that belief, has been referred to as the Myth of the Flat Earth. In 1945, the misconception was listed by the Historical Association (of Britain) as the second of 20 in a pamphlet on common errors in history.

The Flat Earth model is an archaic belief that the Earth's shape is a plane or disk. Many ancient cultures have had conceptions of a flat Earth, including Greece until the classical period, the Bronze Age and Iron Age civilizations of the Near East until the Hellenistic period, India until the Gupta period (early centuries AD) and China until the 17th century. It was also typically held in the aboriginal cultures of the Americas, and a flat Earth domed by the firmament in the shape of an inverted bowl is common in pre-scientific societies.

The paradigm of a spherical Earth was developed in Greek astronomy, beginning with Pythagoras (6th century BC), although most Pre-Socratics retained the flat Earth model. Aristotle accepted the spherical shape of the Earth on empirical grounds around 330 BC, and knowledge of the spherical Earth gradually began to spread beyond the Hellenistic world from then on.

Thales thought the flat earth floated in water like a log. Anaximander (c. 550 BC) believed the Earth was a short cylinder with a flat, circular top that remained stable because it was the same distance from all things. Anaximenes of Miletus believed that "the earth is flat and rides on air; in the same way the sun and the moon and the other heavenly bodies, which are all fiery, ride the air because of their flatness." Xenophanes of Colophon (c. 500 BC) thought that the Earth was flat, with its upper side touching the air, and the lower side extending without limit.