Guardian Exchange was an underground telephone exchange built in Manchester from 1954 to 1957. It was built together with the Anchor exchange in Birmingham and the Kingsway exchange in London – all believed to provide hardened communications in the event of nuclear war; as well as linking the UK government in London to the US Government in Washington, D.C. by means of a secure and hardened transatlantic telephone cable making landfall near Oban and running through Glasgow, Manchester and Birmingham. Today, the underground site is used for telephone cabling. Constructed at a depth of below 35 metres (115 ft), the tunnels are about 2 metres (80 in) in diameter. The exchange cost around £4 million, part of which was funded by the United Kingdom's NATO partners.