Cartagena is a port city on Colombia's Caribbean coast. Located by the sea is the walled Old City, founded in the 16th century, with plazas, cobblestone streets, and colorful colonial buildings. With a tropical climate, the city is also a popular destination for its beaches. You can reach Barú Island, with its white-sand beaches and palm trees, and the Rosario Islands, famous for their coral reefs, by boat.