Once classified tunnels built in the event of nuclear war lie deep beneath Manchester's city centre.
Unknown to the majority of people who walk above them daily, the tunnels built 115ft underground are still guarded around the clock by security staff. The underground network built in 1954 remained a secret for over a decade and their existence was only acknowledged in 1968.
The tunnels run beneath the streets between St Peter's Square and Piccadilly Gardens. The entrances to the tunnels, including two in George Street, are surrounded by barbed wire and security gates.
