Cartagena rewards visitors who prioritize its historic core and coastal escapes. The Walled Old City anchors any trip, its colonial ramparts enclosing cobblestone streets, colorful balconies, and the imposing San Felipe de Barajas Fortress, once the largest Spanish stronghold in the Americas. Inside the walls, Plaza Santo Domingo and Plaza San Pedro Claver anchor the Centro's charm with shaded cafes and street performers. For a change of pace, Rosario Islands Boat Tours ferry travelers to turquoise waters and quiet beaches just offshore. Together these picks balance dense historic sightseeing with easy relaxation, making them the smartest use of limited time in the city.