In September 1971 a group of Ancona cavers dropped a rope into a blowing hole and found a dizzying void: the Ancona Abyss, a chamber in which — the comparison is compulsory — Milan's cathedral would fit comfortably. The Frasassi Caves, opened to the public in 1974, are Italy's most spectacular show caves: a kilometre and a half of halls, crystals and formations growing for more than a million years.
What to see
The Giants, twenty-metre columns; the Candle Room with its calcite tapers standing in water; the Obelisk and the Little Niagara Falls: the tourist route strings together wonders with fairy-tale names at a constant 14 degrees. Outside in the gorge, Valadier's neoclassical temple set inside a cavern is the valley's second coup de théâtre.
Visiting
Guided visits only, seventy minutes on comfortable walkways: booking advised on holidays. For the bold there are caving-adventure routes with helmet and overalls, on reservation. A jumper always, even in mid-August: 14 degrees grants no discounts.
Getting there
The ticket office is at San Vittore di Genga, shuttle to the entrance included; Genga-San Vittore station, on the Ancona-Rome line, is minutes on foot from the ticket office — a rare case of caves reachable by train.
Our editors' tip
Take the first morning slot: smaller groups, cleaner echoes and the Giants almost in private. Afterwards climb to the Valadier temple for the half hour it deserves: the church in the rock under midday light is the encore nearly everyone, wrongly, skips.