The St. Lawrence Fortress in Dubrovnik is often called Dubrovnik's Gibraltar, and it's located outside the western city walls. The fortress has a big court with mighty arches and, as its height is uneven, it has 3 terraces with powerful parapets with the broadest one looking south towards the sea. It lies outside the old town but you can take a look at it when you stand on the walls of the old town.
The inner streets of Dubrovnik are filled with tourists these days.
I wish you all a happy weekend!