San Juan, Puerto Rico SOURCE: tourism.pr.gov
La Puerta de San Juan, or the San Juan Gate, is the last remaining gate in the old city walls. As you walk through it, note the thickness of the defensive wall at this spot—about 4.5 meters (15 feet) deep. Historically, this was the main entrance to San Juan for sailors arriving by sea, and the path through the gate leads directly to the Cathedral of San Juan Bautista. The gate’s massive wooden doors used to be closed daily at sundown to keep the city safe from intruders.