World War One At Home: Detecting the German zeppelins
1 March 2014 Last updated at 15:28 GMT
As part of the World War One At Home project, carried out in partnership between the BBC and Imperial War Museums, Gerry Jackson explores some century-old coastal architecture in Redcar and Sunderland.
Sound mirrors were used in 1915 to detect the sound of German zeppelins approaching.
The sound of the aircraft would be reflected off the concave mirror surface through a trumpet and sent to a listener who would then be able to tell from which direction it was coming.
Two remain in Redcar and Sunderland and councillor John Kelly believes they are a "huge part" of the history of how the east coast was affected by the war.