Britain built giant concrete 'sound mirrors' for early bomber detection before radar

Between 1928 and 1930, Britain constructed three large concrete acoustic mirrors on the Kent coast. These structures, led by physicist William Sansome Tucker, were designed to detect the sound of approaching enemy bombers. The project was initiated following significant World War I air raids on coastal towns. The system was ultimately made obsolete by 1939 due to faster aircraft, background noise interference, and the advent of radar technology.