Cannon balls, Church of the Virgin Mary and the Holy Angels, Loretánské square, Hradčany, Prague

If you look closely at the facade of the original Renaissance church, you will see something that does not belong there. They are cannon balls.
Specifically, these come from 1648, when at the end of the Thirty Years' War left-bank Prague was conquered (and ravaged) by the Swedish army.
Today, Prague is a quiet city. But when you know where to watch, you can find the traces of ancient struggles.