This is absolutely unique!
Policka/Czech Republic - in the middle of 12th century, they built a fortification wall so thick that they placed a tavern inside it, without even compromising the structural integrity of the wall, and indeed, Policka was never conquered. It was pretty slick idea to drink beer while you are defending your town. You can't be stressed out, you have to be relaxed! The tavern is called Heresova krcma.
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From @extremezipliner