Cartagena
One of the most beautiful colonial cities in the Caribbean. It withstood many invasions from bucaneers and pirates, which can partly be attributed to the natural defences of the city, but also to massive military and defense engineering. The city is surrounded by stone walls, and there's even an under-water wall which prevents ships with hostile intentions to approach the city from the sea. One of the hills of Cartagena has been entirely undertunneled with lots of galleries and covered with brick and stone, and is a masterpiece of military architecture: Castel San Felipe. The colorful colonial houses with flowered balconies are really very charming. One has not to fear the mosquitos there, but the street vendors (I'd mind the mosquitos though).
