In 1943, Britain's position in WWII, the target of constant bombardments and attacks by the German troops, was frailer than ever, with the imminent threat of an invasion. That's why its defences were widened and fortified. One of the enterprises that were undertook was the construction of fortified towers along the Thames, which was precisely one of the ways the enemies could've used to take over the British territory. These towers would be able to detect and answer possible attacks. The project was ordered to a civil engineer, Guy Maunsell, who finished it and built in that very same year.
Maunsell was chosen for his expertise in prestressed concrete, a system that had already been used in various bridges and which he used in this project. For the Thames, he planned various sets and types of imaginative fortifications, among which there's this unusual set of towers, the Shivering Sands Army Fort, also known as the U7.
Each tower, built in iron, was set up individually on land and, afterwards, laid in a four-pillar structure of reinforced concrete. The set had various defensive systems (cannons, machine guns, radars, etc.) and was connected by metal footbridges. During the war, it performed a very important role, detecting air raids, the dropping of mines and shooting down several planes and flying bombs.
After the war ended, the Shivering Sands Army Fort remained in activity until 1958, the year it was abandoned by British troops. From then on, without any kind of maintenance and under the corrosive action of the waters, it started to deteriorate progressively. It has already been collided by boats, transformed into a weather station and even worked as a pirate radio station. There were some people who suggested the towers should be brought down, but it remains standing to this day, threatening navigation. It's a magnificent, stern, ghoulish and romantic ruin...