A visit to 'Hell Cave' (note the outline of a devil at the entrance), some 4km north of the Roman necropolis, is quite a heavenly experience. A one-hour tour will take you 1200m from the lower wet area to the upper dry section. Among the highlights, you'll pass a 4m-high waterfall, the Silent Hall with perfect acoustics and the Hall of Fantasy, where stalactites and stalagmites become snakes, pigeons, cauliflower and frogs. It's 10°C in there and very slippery; take a wrap and wear sturdy shoes.
