Several years ago we were on an escorted land tour that included Dubrovnik and a gazillion people thronging the streets. We finally broke away and went up a side street/alley. Then another one and finally found a pub where had some lunch and a glass of wine. What a mess. We heard later that UNESCO had threatened them with revocation of the heritage status if they didn't do something about it. It was clearly the cruise ships, multiple ones in a single day. I've heard that it's gotten better so maybe they did. Just an observation.