Was knowledge of the New World's existence truly unknown to everyone in the Old? Coloumbus was far from the first person to stumble upon the Americas. Surely someone else wrote about or mapped it?

by Roses_Are_Red
Mictlantecuhtli

There's always room for discussion, but perhaps the sections Travel and contact across the Atlantic before Columbus and Historians' views of Gavin Menzies' "1421: The Year China Discovered the World" in our FAQ will answer your inquiry.