Trevanion Caves, a large complex behind Dover Sports centre that was adapted to air raid use during WW2. This cave is linked by a long tunnel (Guilford or Guildford Tunnel) to Athol terrace caves and aothers.
Silent footage from March 2007 showing the semi-derelict building at Westmount, Dover. End of the clip shows the sealed entrance into the air-raid tunnel that linked up with the system at Winchelsea Quarry.