The Listening Mirrors of Denge
Huge concrete dishes stand on a lonely stretch of the Kent coast, built to listen for enemy aircraft.
What was reported
On the shingle at Denge, near Dungeness, stand three strange concrete structures: two curved dishes, about 6 and 9 metres across, and a long, curved wall about 60 metres wide. Seen across the flat, empty landscape, they look like relics of some forgotten purpose.
They were built around 1930 as acoustic mirrors, to give early warning of aircraft approaching over the Channel by focusing the sound of their engines onto microphones.
Explanations offered
The mirrors could pick up aircraft some minutes before they could be heard by ear. But faster planes, and the invention of radar in the mid-1930s, made them obsolete almost as soon as they were finished. They now stand in a nature reserve.
- When
- Built around 1930
- Where
- Denge, near Dungeness, Kent, England
- Witnesses
- Walkers on the shingle
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.