The Advanced Defense Line (Spanish: Línea Avanzada) is a historic district consisting of four structures that formed part of the eastern defensive system of the Islet of San Juan in San Juan, Puerto Rico.
The Advanced Defense Line (Spanish: Línea Avanzada) is a historic district consisting of four structures that formed part of the eastern defensive system of the Islet of San Juan in San Juan, Puerto Rico. (en)
The Advanced Defense Line (Spanish: Línea Avanzada) is a historic district consisting of four structures that formed part of the eastern defensive system of the Islet of San Juan in San Juan, Puerto Rico. (en)