I used to believe the Elgin marbles were actual huge round marbles ... as opposed to carvings from antiquity. This was until fairly recently.
A childhood belief about history

others believed things like this
- i used to belive that 100 was the biggest number in the world "i got at least a hundred marbles."— dan harris
- I thought until fairly recently that bacon came from the skin of a pig and that's why it was so thin— Nate
- for the longest time every i used to think that Prince's "Raspberry Barret" said "round merry go round"— lin
- I used to think that a conductor while conducting told the players what to play as opposed to their music.— Daryl
- When I was a child, I used to believe my parents were superheroes, like the fairly oddparents!Anon
- I used to think that raisins were dead flies. I only recently started to eat them again.— Toinette'