In great detail, davel, that is if you are referring to the "Guardian Tunnels". Even a picture of the pit head style winding gear used situated near to Piccadilly Gardens.
These tunnels were built in the major cities in the UK in the 1950's as part of the national nuclear defense system. Funding came from NATO. Manchester's cost in the region of £4millon, mucho dosh at the time.
Meant to be secret but revealed in the late 60's by none other than John Stonehouse MP the then Postmaster General of the GPO & Telephones. This infamous MP faked his own death from a beach in Miami, later to turn up in Melbourne, Australia a few months later. The Australian Police thinking they had caught Lord Lucan by all accounts. :lol:
:offtopic: but interesting eh!