The largest prehistoric man-made cavern in the world may be hidden under a north Wales peninsula.
The cavern is part of a Bronze Age copper mine complex which was first uncovered in 1987 at Great Orme’s Head near Llandudno.
Archaeologists excavating the 4,000-year-old site made their latest discovery 130ft below ground in December and have estimated it is at least 50ft in length.
They know the roof area is large, but will have to dig down through many layers of silt before they discover exactly how deep it is.
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