The Fortaleza Ozama is the oldest European military fort in the Americas, built between 1502 and 1508 at the mouth of the Ozama River where it meets the Caribbean Sea. The Torre del Homenaje (Tower of Homage) at its centre is the defining structure — a square medieval tower that has served successively as a military command post, a prison, and, for the last century, a monument. You can climb to the top for good views over the river and the surrounding colonial streets.
The fortress grounds are open to visitors and make an easy combination with the Zona Colonial. The thick stone walls and the old cannons pointing over the river give a vivid sense of the strategic importance of this location in the early colonial period.