This building, that sits between St James Street and Back George Street, isn't one that most people are likely to walk by since it is rather off the beaten track.  It is also unlikely to attract the eye and clearly every effort has been made to keep people out.  It sits behind high brick walls topped with a significant barbed fence.  What few entrances there are, are less than welcoming.  The fact is that this is one of a small number of entrances into Manchester's secret Cold War underground telephone exchange known as Guardian.

Built in the 1950s, it involves a significant tunnel system that runs from Ardwick into the city centre and on to Dial House beside the Irwell in Salford ....



.... and on to a point on Chapel Street near Salford Cathedral. 



At that time the thinking was that it was important to create a secure communication system capable of withstanding a nuclear attack, and along with this one in Manchester, there were others in Birmingham and London.  Apparently, the Guardian exchange was permanently manned by around 50 engineers.  In the event of an emergency the tunnel could be sealed by a 35 ton concrete slab door.  Inside there was living accommodation  and supplies of food and fresh water.

The system was built in secret and stayed a secret until 1968.  The underground telephone exchange came into use in December of 1958 and was in continual use until its closure in 1970.  The tunnels are used today by BT to carry cables between exchanges within the city.  In 2004 a fire in the tunnel caused major damage to the cable system affecting 130,000 homes and businesses and disrupting emergency services.