This Tunnel Was Built for Mining… Then Used for Nuclear Secrets - Excelsior Mine

Exploring one of Cornwall’s most mysterious underground locations — the Excelsior Tunnel beneath Kit Hill. What started as a 19th-century mining venture was later transformed into a secret Cold War testing site. In 1959, the British government used this very tunnel to carry out classified explosive experiments under Operation Orpheus, designed to study how underground nuclear blasts could be detected… or hidden. Join me as we walk through this eerie tunnel system, uncover remnants of Cold War science, and stand right above the deep shafts where the detonations took place. This is more than a mine — it’s a forgotten piece of Britain’s nuclear history. Don’t forget to like, comment, and subscribe for more hidden history, urban exploration, and underground adventures! #ExploringWithConnix #ColdWar #UrbanExploration #ExcelsiorTunnel #KitHill #CornwallMines #AbandonedPlaces #ColdWarSecrets #HiddenHistory #OperationOrpheus #NuclearHistory #CornwallExplores #UrbexUK #UndergroundExploration