You knew this was coming. At some point in time, you just knew. I'll skip straight to the facts, folks. I'm not going to use this space to bag on President Trump or the European populists who want to keep refugees from the Middle East out. Walls have been a part of human history as long as trade and government have been a part of human history. It's just a fact of life. Here are 10 walls in history that have actually been built:
10. Let's start off with the easiest one: the Great Wall of China. Technically a series of fortifications that began in the 7th century BC, the Great Wall of China as it is popularly depicted - stone walls with carefully-placed watch towers hemming and hawing through lush, green mountain sides - was built to keep invaders from the north out.