Prometheus Cave is the largest cave in Georgia, and the six halls you walk through are lit in colour and named after a Greek myth. It lies under the limestone hills of Imereti in the west of the country, near the old spa town of Tskaltubo. Twenty-two chambers have been dissolved out of the rock by water, and those six are strung onto a single paved walkway 1.4 kilometres long. Going down takes you about an hour and is gentle the whole way. Stalactites bristle from the ceilings, heavy stalagmites climb off the floor, and sheets of flowstone hang down the walls in folds that look caught mid-pour. Banks of light wash the columns purple, crimson, turquoise and gold, each hall set to its own colour, so the same rock reads differently from one chamber to the next. The air holds a damp 14°C all year, so you step out of an Imereti summer into something nearer autumn.
At the far end the walkway meets an underground river, and instead of turning back you can leave by boat. The ride is short, the ceiling low and the water cold, and it is called off whenever the river runs high. The names on the halls belong to this region rather than to Greece. Western Georgia was ancient Colchis, the kingdom Greek myth sent Jason and the Argonauts to for the Golden Fleece, and Medea was a king's daughter there. So the chambers are Argonauts, Colchis and Medea, and the cave itself took Prometheus in 2010. The Caucasus already had a fire-stealer. Amirani took fire from the chief god and was chained to a peak for it, an eagle tearing at him each day, and the two stories run so close together that scholars still argue over which came first. Local legend is not in any doubt, and the rock it points to is not this one and not underground: Khvamli, the flat-topped massif standing over these same hills.