This 16th-century fortress located in the Colonial Zone of Santo Domingo was built by the Spanish and is recognized today as a UNESCO World Heritage site. History buffs can explore La Fortaleza—which is the oldest European-style military building in the Americas—and learn more about how this old-school castle that once guarded the port of Dominica Republic’s capital city. Travelers can explore the grounds of this imposing castle that once served as a prison on their own or with the help of a local guide. A climb to the Torre del Homenaje offers incredible 360-degree views of the city, and a nearby powder house and rows of cannons reflect the fort’s important military history.