Without a doubt, Cartagena's old city is its principal attraction, particularly the inner walled town consisting of the historical districts of El Centro and San Diego. El Centro in the west was traditionally home to the upper classes, and San Diego in the northeast was previously occupied by the middle classes. Both sections of the Old Town are packed with perfectly preserved colonial churches, monasteries, plazas, palaces and mansions, with balconies and shady patios that overflow with bright flowers.
With its modest architecture, the outer walled town of Getsemaní is less obviously impressive, but as it's far more residential and less sanitized, it offers plenty of atmosphere and is well worth exploring. In recent years it has become a backpacker hub, and gentrification has come astonishingly quickly – the area is full of trendy restaurants, packed cocktail bars and salsa clubs, and almost as many boutique hotels as the inner walled town. A beautiful walkway alongside the Muelle Turístico de los Pegasos links Getsemaní with the Old Town.
The Old Town is surrounded by Las Murallas, the thick walls built as protection against enemies. Construction began towards the end of the 16th century, after a siege by Francis Drake; until that time Cartagena was almost completely unprotected. The project took two centuries to complete due to repeated damage from storms and pirate attacks. It was finally finished in 1796, just 25 years before the Spaniards were eventually expelled.
Cartagena's old city is a fortress in itself, yet there are several more fortifications built at strategic points outside the city, many of which are worth visiting. The most famous of these is the massive Castillo de San Felipe de Barajas, which looms over the city and is perhaps the most impressive colonial fortress in South America. History buffs will enjoy visiting other, less well-known fortresses, but always check the latest safety information with your hotel or a travel agency, as some remote sites may not be safe for you to visit alone.