In Strijensas we find three defensive structures at a single location: a dike, a casemate and an air lookout tower.
The air watchtower was part of the network of lookout towers used during the Cold War. From the tower, troops could hear Russian planes that were using a low approach in an attempt to evade radar detection up to 8 kilometres away. A total of 138 of these lookout towers were built in the Netherlands from 1951 onwards. Today, there are 17 still standing, many of them in poor condition. The tower in Dordrecht is the last preserved tower in the province of Zuid Holland. It is the lowest air watchtower in the Netherlands and the only one from WWII that was built on top of a concrete casemate.
The casemate under the tower was built in 1937. It is also known as a V.I.S. (Voorschrift Inrichten Stelling) casemate. The river crossing and the Moerdijk bridges were monitored with a machine gun from the casemate. Many traces of original use can still be seen, such as the steel doors and shooting holes for the machine gun. There are even traces of impact on the outside.
You can climb the air watchtower on Bunkerdag. There is a magnificent view of the Hollandsch Diep river crossing, the Dordtsche Kil and the Moerdijk bridges from the lookout. A large part of the Hoeksche Waard National Landscape can be seen from the other side.
Please note: visitors must climb several narrow stairways to gain entry to the casemate and tower. This location is not suitable for people with mobility problems.