Swiss soldiers began guarding Vatican City in 1506.
At the time Swiss Cantons were very poor, and men started emigrating to other places in hopes of finding a better future. Most of the jobs available to immigrants were as soldiers. Swiss soldiers were seen as loyal, courageous, and hard-working, and as a result Pope Julius II invited them to protect him and the Vatican.
While Europe is famously dotted with castles, some of the world’s oldest stretch across the Middle East and Asia as well, revealing the deep roots of fortified construction in human civilization.