Make for the plunging Frasassi Gorge for a "journey to the centre of the Earth" through the Grotte di Frasassi, one of Italy's largest and most famous complex of caves. An ideal jaunt for a rainy day.
Some 13 km of limestone caverns have so far been explored and it is reckoned that they may run for up to 35 km. Only one and a half km of this crystalline wonderland is open to the general public. Equipped with walkways and theatrical lighting, it includes the awesome Grotta Grande del Vento, Europe's largest single cavern, so vast that Milan Cathedral would fit comfortably inside, and some of the most extravagantly fanciful stalagmites and stalactites you are ever likely to see. Even claustrophobics shouldn't find it too challenging.
The guided tour lasts for around an hour; dress up warmly as the temperature inside is a constantly low 14 degrees C. Be warned that it can get quite crowded in high summer.
The highish admission charge is well worth it. From Nov to Feb there are tours daily at 11.00, 15.00 and 16.00; from March to Sept daily tours at 9.30, 11.00, 12.30, 15.00, 16.30 and 18.00 with continuous tours in Aug from 8.00 until 18.30. For information telephone +39 0732 97211 or fax: 0732 972001.
Even if you don't have time to see the caves, stop to admire the splendid backdrop of the Frasassi Gorge and the Romanesque church in the little spa of San Vittore delle Chiuse (right by the cave ticket office and car park). This tiny, perfectly square chiesetta was built in the 12thC on chastely simple lines and is one of the prettiest of its kind in the Marche. (To see inside ask for the keys at the tobacconist's opposite.)