Castellana Caves

The first thing you notice is the air. It is cool and damp, and it smells faintly of wet stone and earth. Above you, a round opening frames a patch of sky. Below you, the ground drops away into shadow. You are standing at the edge of a vast natural shaft in the limestone of southern Italy. A single beam of daylight falls into the dark, and everything beyond it is quiet.

This is the entrance to the Castellana Caves, in the region of Puglia, the heel of the Italian boot. The town above takes its name from them: Castellana Grotte. Up on the surface, you find olive groves, dry-stone walls and white houses. Down here, a long chain of chambers and corridors runs through the rock. The full route stretches for roughly three kilometres underground.

The great opening above you has a local name: la Grave, which means something like 'the pit'. It is a sinkhole, roughly sixty metres deep. It formed when the roof of an underground cavity collapsed long ago. For centuries, it was the only part of the cave system that anyone could see. People in the farmland around it knew it well, and many of them avoided it.

Locals say the pit carried a dark reputation. According to popular tales, mist sometimes rose from its mouth on cold mornings, and some people imagined it as a doorway to the underworld. Whatever people believed, the Grave was also used in a very practical way — as a place to throw rubbish. For a long time, nobody knew what lay beyond the bottom of the shaft.

That changed in January 1938. A speleologist named Franco Anelli came to explore the pit. Speleology is the scientific study of caves. Anelli was lowered down into the Grave on ropes, with help from local men. At the bottom, he found passages leading away into the dark. Those passages led to the cave system you are about to walk through. Today, his name appears across the town, and a museum of speleology nearby carries his name.

It helps to know how a place like this forms. The land here is limestone, laid down long ago as sediment under an ancient sea. Rainwater picks up a little carbon dioxide from the air and soil, and it becomes slightly acidic. Over immense spans of time, that water dissolves the rock and opens cracks into channels, and channels into caverns. Geologists call this kind of landscape karst.

As you move deeper, watch how the formations change. Water drips slowly from the ceiling, and each drop leaves behind a tiny trace of calcite, a pale mineral. Hanging formations are stalactites. Rising formations are stalagmites. When the two meet, they form a column. Some of these shapes took many thousands of years to grow, one drop at a time. So please do not touch them. Oils from human skin can stop their growth.

The guides who lead you through the caves give many of the formations names. Some shapes look like animals, some like figures, and some like familiar objects. You may hear names such as the Owl, the She-Wolf or the little Madonna. These names come from the human habit of finding faces in stone. Try to see the shape before your guide points it out. Sometimes the resemblance is clear, and sometimes it takes imagination.

One stretch of the route has a name that surprises many visitors: the Desert Corridor. Here, the walls turn warm shades of red, ochre and orange. Iron and other minerals in the water give the rock these colours. Underground, the effect is unexpected. You walk through a narrow passage that feels dry and sunlit in colour, even though no daylight has ever reached it. Notice how the lighting brings out the layers in the stone.

The temperature down here stays cool through the whole year, at around sixteen degrees Celsius. In midsummer, when the fields above are hot and bright, the caves feel almost cold. In winter, they can feel mild. The humidity is very high, and the floors can be wet. Listen as you walk. You will often hear the soft tick of water dripping somewhere in the dark. That sound means the cave is still growing.

The longest tour ends in a chamber that many visitors consider the finest part of the whole system: the White Cave, or Grotta Bianca. Here, the formations are a pale, almost glowing white. The calcite crystals are so pure that they look like alabaster, a soft, translucent stone used for sculpture. Some surfaces sparkle under the lights, as if frost covered them. Thin, delicate formations grow out at strange angles.

Pause for a moment in the White Cave and think about what is missing. There is no wind here and no birdsong, and the seasons do not change. The only change comes from water, moving through stone, slowly and patiently. Everything you see began as a single drop. Before 1938, no human eye had seen this chamber, and it existed in total darkness.

When you climb back toward the surface, the air will warm and the light will return. Look up once more at the circle of sky above the Grave. Think of Anelli hanging on his rope in that shaft, not knowing what waited below. Then step out into the Puglian sunlight, among the olive trees and white walls. The caves are still there under your feet, silent and dark, and the water is still at work.