This is Dated but still relevant, Ignore the online tool it no longer works,
https:// www.wired.com/2015/09/now-can-find-nsa-gchq-spied/
GCHQ, Cheltenham, UK, looks like its ready for take off,
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The Doughnut
The Government Communications Headquarters is the signals arm of British intelligence. GCHQ basically has the same charge as the U.S. National Security Agency, and like the NSA, has an awesome office building. Completed in 1993, the facility is like a prototype of Apple’s spaceship campus under development. Spies call GCQH headquarters “the Doughnut.”
https://
en.wikipedia.org/wiki/Government_Communic