From homepage:
Unlike real museums, these galleries are built by countless generations across thousands of years, using only rock as a surface material and natural pigments and ochre as colour. The rock art galleries of Acacus (Akakous) are an intricate collection of cave sites integrated along a network of valleys across the mountains. In a sense Acacus is a city devoted to art galleries (wadis), which collectively form a massive library of ancient and still obscure data.

Website: http://www.temehu.com/libyan-art-galleries.htm

Reuters Video: Rock Art under threat in Libya