One of the three remaining gates into the old city, the lofty red portal known as the Puerta de San Juan is a popular photo stop. Spanish ships once anchored in the cove just off these ramparts to unload colonists and supplies, and this tunnel through the wall dates from the 1630s.
Once there were a total of five gates, and the massive wooden doors were closed each night to thwart intruders. Turn right after passing through the gate and you can follow the Paseo del Morro northwest, paralleling the old city walls for approximately three-quarters of a mile. Pause on one of the benches along the western side that have fine harbor and sunset views.