The medieval stone wall surrounding the charming seaside city of Dubrovnik is well worth the walk, but head north a bit to sleepy Ston for a more intense wall walk that is not for the faint of heart...
Breathtaking views come with a price tag, in this case, heights, and while this ancient wall is completely safe & sturdy, complete with a guard rail on both sides, if you have any fear of heights you might consider sitting this one out and meeting your crew at the end of the walk, in Mali Ston, where you can get a head start on fresh oysters & crisp Croatian white wine- two things that the region is knows for.
I am actually afraid of heights, but found this walk to be not only physically exhilarating (the walk up is quite steep and really gets the blood pumping) but also beautiful and a lot of fun! It doesn't take long- 1.5 hours and provides beautiful views of the area. Plus, the towns of Ston & Mali Ston are rather charming- very inconspicuous and low key- a nice juxtaposition to the over-crowded yet beautiful Dubrovnik.
One thing to note- wear comfortable walking shoes with tread as the stones on the wall are ancient, and quite smooth from the sun and time and therefore slippery when coming down. And of course, don't forget your camera!