By e-mail I received the following question:

Can tourists visit the petroglyphs in Val Camonica? Are they open to the public without a reservation?

Several locations seem to be open to the general public, according to the two reviews on our website.
Anyone more info?

This link gives some limited info (usual Italian closure on Mondays etc) and contact numbers/e-mail
http://www.rupestre.net/alps/valca_naquane_visita.html

This one (click to 2.2 for visitor info and use Google translation if you don't speak Italian) gives more precise opening hours (and closing days)
http://digilander.libero.it/archeocamuni/

There are Valcamonica sites outside the Naquane area but we only visited that one - and all the evidence is that it is the best if you can visit only 1 area. This link shows the other centres quite well and should lead on to more info if required.
http://wanderingitaly.com/a/valcamonica-map.htm