From the ceiling of one chamber hangs a calcite straw 2.5 metres long: the longest known in Italy, a thin tube grown drop by drop. The Borgio Verezzi caves, also called Valdemino, are a karst system found in 1933 and fitted out for visits in 1970. The minerals dissolved in the rock have earned them a name as the most colourful show caves in Italy: white, yellow, red and every shade in between.
What to see
The tourist route runs 800 metres and skirts a series of small lakes fed by the Rio Battorezza, the little underground stream that carved much of the system. The colours shift from chamber to chamber according to the minerals in the rock: they are what sets these cavities apart from all the others.
Besides the longest straw, the ceiling carries many more: hollow tubes as thin as a drinking straw, which grow at the tip and not in girth. In some side hollows prehistoric bone remains have been found, dated between 500,000 and 750,000 years ago and lodged in the fissures of the limestone long before anyone came down here.
Visiting
The entrance is on the edge of Borgio, the seaside part of the municipality, in the province of Savona; you go in with a guide, in groups, and the circuit follows an almost level path. Underground it is cool and the humidity stays high in every season: a sweatshirt is useful even in August, and closed shoes with a gripping sole help on the wet stretches.
Our editors' tip
Ask the guide to switch off the lights for a few seconds: in the dark only the dripping is left, and it is the most direct way to grasp what dug all this. Then, when the lamps come back, look for the straws against the light and see how slender they are next to the stalactites beside them.