Dubrovnik old city is a gem. Compact and gleaming in the sun. It’s surrounded by a city wall which has a lot of steps with fab views but strenuous in the hot sun. Dubrovnik has pretty bars, restaurants, a cathedral, a couple of monasteries incl a Franciscan monastery (which has a charge) and its lovely cloister and many churches inc St Blaise, patron of the city. His statue is everywhere. It has a Main Street (Stranum) with lovely streets branching off but if you don’t want to walk many steps, go to town hall with the clock, turn left after a couple of steps and then turn left again where there is a lovely street of restaurants.
Dubrovnik has a harbour where you can travel to the nearby island of lokrum and futher afield to captivating Cavtat.
It does get busy when the cruise ships are in but go after 5 and it should be not as busy. It can get hot too esp in July and August The evening time is a nice time for a stroll. It’s about 25 mts to airport to the south. The coastline is breathtaking. One more thing there is a cable car which can get busy going up to Mt Syd with your postcard view of Dubrovnik and surrounding islands.