the question is: As weaponry and war techniques advanced, so did the design of a city’s defenses. What changes

the question is: As weaponry and war techniques advanced, so did the design of a city’s defenses. What changes took place to the city at the end of the Middle Ages (Medieval era) as a result of the appearance of gunpowder? Note that this is not a question about military history, but about the city’s evolution in this context.