A series of tunnels that run underneath central London and were used for communications during the Cold War have gone on sale for an estimated £5m.
The deep tunnels were built in 1940 and used as air raid shelters holding 8,000 people during World War II. They were used by MI6 in the last two years of the war.
They have since been used as a "reserve war room", public record library and the telephone exchange which connected the Cold War hotline between the presidents of the US and USSR.
In its days as an exchange it housed about 80 workers, who enjoyed a canteen and recreation room - complete with snooker tables.
Access to the mile-long system of horizontal and vertical shafts is in lifts through unmarked doors in the street on High Holborn.
BT has owned the tunnels since 1986 and tried selling the site 10 years later but with no luck. It expects offers of about £5m for the 77,000 square feet of space.