Many cities in Germany (and Europe in general) have a ton history, they were mostly old walled fortresses - which was a defense mechanism back in the old days. The great thing is that these walls and structures remain in tact today and the cities flourish behind them. What is great about these cities is that you can still explore and walk the great walls that served as protection back in in the historic times of Germany. You can see why these walls served as such important defense mechanisms and why they worked so well. They are tall, steep and reinforced. I can only imagine the work and engineerings that went into their creation.