Ston Walls
In order to protect the enormously valuable Ston salt pans, in 1333 the Republic of Dubrovnik built a 7-km (4½-mile) fortified wall (purportedly second in length only to the Great Wall of China), effectively controlling land access to the peninsula. The stretch of wall that remains is 5½ km (3½ miles) long, and you can walk atop it from Ston to Mali Ston, which takes about 40 minutes and offers incredible views of the channel and the salt pans. It's a strenuous walk, so good shoes and a moderate level of fitness are recommended.
