Puerto Rico’s choice placement in the Caribbean and the political and military value of the San Juan Bay were great incentives for foreign attacks. Spanish colonizers recognized the importance of defending San Juan from these attacks and, in the middle of the sixteenth century, began construction of the city’s defense system with the towers at El Morro and La Fortaleza. It was between 1634 and 1638 that the city walls were first built. They were later modernized in 1765 and raised to their current height. These three-mile long fortifications, were crucial to deflect attacks by the British and the Dutch, as well as to ward off pirates. Today you can take a walk along the walls that circle the northernmost tip of the city, by setting off on the trail beginning next to La Puerta de San Juan.