The British countryside has been littered with bizarre concrete structures. Nobody knew the reason they were built and if they had any function, until now. These were built in the earlier 20th century and were used as acoustic mirrors.
The first efficient radar system in the world was invented by Scottish physicist, Sir Robert Watson, in 1935. It detected aircrafts from a distance of 100 miles using radio waves. British military might have been onto something even before that and you can still see the remnants scattered among the British countryside.
Before the use of radars we know today, Dr. William Sansome Tucker made a system known as acoustic radars. These were used to detect enemy aircrafts in the World War I.
Even though their range was nowhere close to 100 miles, they did have the ability to detect aircrafts 15 miles away. This allowed them some time to prepare before the bombers made their run.
Even though this technology was phased out a century ago, a great number of them are still standing tall along the English coastline.
These bizarre concrete structures are found in different parts of England and serve as attractions for tourists.
There were hot-wire microphones with the structures that detected the sound waves of the approaching aircrafts and provided a 15-minute warning before the craft appeared.
The majority of the mirrors detected at a distance of 15 miles but there were some that could do so at a range of 25 miles.
When aircraft designers started building quieter jets, these mirrors were pretty much rendered useless.
It is rare to see something so well preserved after so long. Even though these are no longer used by the British to warn about incoming aircrafts. You can still visit them and see these bizarre concrete structures for yourself.