The Frasassi Caves (or Grotte di Frasassi) is one of the largest subterranean cave systems in Europe. It was discovered fairly recently, in 1971, and has been open to public from 1974. Of the 18 kilometres of underground caves that have been explored, just 1 kilometre is open to guided public tours. It’s likely that the cavern system is much larger, some estimates putting it at 35 kilometres long. […]
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