ELI5: Explain Like I'm 5

Labarum

Okay, so imagine you have a special flag that you wave to show everyone who you are and what you believe in. Well, long, long ago, the Roman Empire had a special flag like this called a labarum.

It was a very important flag because it had some special symbols on it. The first symbol was a letter that stood for the Roman Emperor's name. His name was Constantine and the letter was "Chi" (pronounced "Kai"). The second symbol was an "X" which represented a very important religious symbol called the Cross.

The labarum became even more special to the Roman Empire after a big battle. In the battle, the emperor Constantine saw a vision of the Cross in the sky and heard a voice that said "By this conquer." So the labarum became a really important symbol of the Roman Empire's power and Christian beliefs.

Even though the Roman Empire isn't around anymore, we can still learn about it and the labarum is a big part of that history.