The gravina — the word means 'ravine' in the local dialect — is a deep limestone gorge carved by the river of the same name over millennia. The walls are riddled with cave dwellings, some of them inhabited from the Neolithic period through to the 18th century. Walking the path along the valley floor gives a completely different perspective on the town above: the cave openings, the layers of rock, and the silence broken only by the river make the setting feel genuinely remote.
The ravine is the defining feature of the town and the reason for its name. Most visitors see it from the bridge above; it's worth the extra time to descend into it. The path starts near the cathedral and takes about 20 minutes one way to reach the bottom.