The Vatican - The original “Flat Earthers”
Didn’t Galileo get sideways with them over some crazy heliocentric theory of his?
Actually, the Church never believed in a flat earth. The Church had, in fact, taught a spherical earth as far back as it had existed due to Europe’s adoption of Aristotle’s cosmology.
The myth that people in the Middle Ages thought the Earth is flat dates from the 17th century as a slander by Protestants against Catholic teaching. It was later used by atheists to impugn fundamentalists.