I know that it seems like simple clickbait, asking a question that is ridiculously easy to answer, but bear with me.
Conventional wisdom today is that, in Columbus’s time, it was widely known that the world is spherical, and that Washington Irving introduced the myth that there had been widespread belief in a flat earth in his book A History of the Life and Voyages of Christopher Columbus. Seemingly reliable sources recount this. At least the second part of this, however, is not true. Consider the following:
Irving does not actually say that scholars believed the earth to be flat in the 15th century. Rather, he recounted this as only one of several beliefs prevailing at the time, and a minority view. He suggested that a majority of scholars did believe the earth to be spherical, but supposed the antipodes to be uninhabitable or the size of the earth to be too great to allow Columbus to reach India. (The last of these, of course, was true.)
The modern supposition that people in the middle ages believed the earth to be flat did not originate with Irving. It is easy to find 18th century books retailing the story that people thought the earth was flat until Columbus showed otherwise. Such books, some of them textbooks, continued to be written well after Irving’s time. Irving actually gave the medieval thinkers fairer treatment than was then prevalent.
Long after Columbus, writers continued to feel that they had to demonstrate by argument that the world is spherical. Seventeenth century texts take the trouble to explain that we can tell the world is round because we can see its shadow when there is an eclipse of the moon, and because an approaching ship on a calm sea first reveals its sails, and only later the lower parts of the ship.
So my question is, what do we really know about what people believed at the time of Columbus? Obviously there have been learned men who knew the earth to be spherical since classical times. But how widely accepted was this? For example, would an educated non-scholar, such as a monarch or noble, have thought the earth to be round or flat?