Kumistavi caves near Kutaisi in western Georgia is the biggest and most amazing network of caverns in the country.
The little sister of this huge complex is Sataplia cave. Nearby, there are dinosaurs' footprints!
But the main jewel is the Prometheus cave, with its breathtaking views of stalactites, stalagmites and underground rivers.
"We are in a spectacular spot here, at the heart of a labyrinth of caverns branching out for dozens of kilometres underground," said 'Postcards' reporter Claudio Rosmino.
"Just think, some of these rocks have taken up to 60 million years to form!"
Today, visitors to the Prometheus Cave Centre can enjoy a magnificent 1.2 km walk, but those who discovered this place, in 1984, reached it through a very narrow passage.
"We were literally in the mud up to our ears! When we arrived in this huge hall, this amazing underground system, we were bursting with happiness," remembered speleologist Amiran Jamrishvili.
"We could not wait to go out and share this with all the other speleologists!"
And no visit would be complete without a boat trip on an underground river in which the traveller can emerge from the magical cave - back into the outside world.