These are two of the three ‘Listenening Ears’ at Denge, Kent. They were built in the 1920’s -1930’s as experimental dish shaped microphones which were able to hear aircraft approaching from France / Europe in the defence of England. They were made redundant by radar during World War 2.
The third concrete ‘mirror’ looks like a slightly curved wall.
Above is how the photograph would look as a Framed Print.