Cartagena de Indias is a historic city in Colombia known for its well-preserved colonial architecture. Some of the top attractions mentioned in the document include the 11 km of Alcazar walls that encircle the old city, the Rafael Nuñez House Museum which was the home of a former Colombian president, and the Mud Volcano of Totumo which is known for its therapeutic mud. The document also recommends visiting several beaches, parks, and neighborhoods that showcase different aspects of Cartagena's culture and history.