A fortified town on the Adriatic coast, Kotor sits nestled in the Bay of Kotor, a natural fjord characterized by ancient ruins, winding streets and more charm than one can ask for.

"Pearl of the Adriatic," Dubrovnik sits in southern Dalmatia along the Adriatic Sea and is known for its unique Old Town, enclosed with massive stone walls from the 16th century and packed full of delicious seafood restaurants and charming boutiques.

Established in 1521 by the Spanish, Old San Juan is the oldest city in the United States and its territories. There you'll find colonial architecture, impressive fortifications, cobblestone streets, open plazas, and hidden patios. Nearby, el Yunque National Forest is the sole tropical rain forest in the U.S.

Known since the colonial era as Cartagena de Indias, Cartagena is made up of a charming walled Old Town, founded in the 16th century, with squares, parks, cobblestone streets and colorful colonial buildings. The tropical climate also gives way to spending days at the beach but the best are only accessible by boat.