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 noncommercial.
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 disturbing them.