Museum Barbican in Krakow

You're standing by the Kraków Barbican, that chunky round fortress of red brick sitting in the green of Planty Park. A barbican is a fortified outpost in front of a city gate, and this one is the best preserved in all of Europe. Have a look at the roofline. Seven little turrets poke up above it. And see all those small openings in the wall? They're embrasures for firing through, a hundred and thirty of them.