The rock art national park is about 15 minutes walk from Capo di Ponte - I couldn't find it exactly on the map, so have put in the latitude/longitude for the town itself - hope this helps (it's well sign-posted on the roads as you drive up to Capo di Ponte from the south). The following website has extra visitor info: http://www.rupestre.net/alps/valca_naquane_visita.html
Our guidebook said that the rock art at Valcamonica was scattered through a light industrial area - gave a really gloomy impression. But although the overall valley is a bit industrial, the area where you view the rock art is much nicer, tucked away in a wood. There's an info/ticket point where they give you a map, good accessibility, info boards, and (if you care about such things) excellent loos.
Most of the rock art is on huge, embedded rocks. The images date over thousands of years - prehistoric to medieval, but the majority are iron age. Images of hunting, fighting, farming, riding, dancing, houses on stilts with long ladders trailing up, a giant human figure wearing antlers, axes and wild animals. Feels like a gift to have such direct communication from a prehistoric society.