There are plenty of sources on the Internet giving "amazing facts". Often they turn out to be not particularly amazing, or even completely untrue.

However, I was truly amazed by one fact that I happened on by chance recently.

What would you say was the world's largest encyclopaedia before Wikipedia? Apparently it was the Yongle Encyclopaedia and it held the record for precisely 600 years.

Wow. I'd never heard of it.