The grottoes are fascinating otherworldly caves that date from prehistoric times: excavations have revealed that they were inhabited 42,000 years ago, making them the oldest known settlement in Europe. Don’t forget a jacket, and leave the high heels at home, as paths are wet and slippery. Hard hats (provided), and a certain level of fitness and mobility, are required. Located 40km southeast of Salerno on the northwest cusp of the national park, the complex is refreshingly non-commercial.
Although it extends over 4800m, only around half of the complex is open to the public. The one-hour tour winds through a route surrounded by extraordinary stalagmites and stalactites, and a mesmerising play of colours, caused by algae, calcium and iron, which tint the naturally sculpted rock shapes.
The tour culminates in a cavernous lunar landscape – think California’s Death Valley in miniature – called the Caverna di Bertarelli. The caves are still inhabited – by bats – and visitors are instructed not to take flash photos for fear of blinding them.