For history & culture, Ston Day Trip (Walls, Salt & Oysters) delivers.
A low-key, authentic alternative to Dubrovnik's crush — you can hike the 'European Great Wall' with hardly anyone around, see working salt pans unchanged for centuries, and eat oysters pulled from the bay below. The catch is there's not much else to do and you need a car or tour to get there; it's for travellers who like quiet history and don't mind a short drive.