the walls of the fortified town of naarden. although the fortified town was first founded in 1350 CE, the current fortifications date from the 17th century and features huge bastions, giving the city a star-like shape from the sky. during the 19th cenruty, the fortifications were enhanced by the building of a number of underground barracks, depots and mortar casemates inside the bastions (the lowermost fortress shows one of these structures).
the fortified city was also one of the northernmost defences of the dutch waterline; a line of innundations and over 60 forts and fortresses that runs north to south through the netherlands (more info: [link]
panoramio link (find out where this shot was taken): [link]