West of Tucson is a Bureau of Land Management campground which has a pile of rocks with more petroglyphs than I have ever seen in one place. Many natives, explorers, and settlers passed through this area over the last 1000 years; many left their marks in the varnish on the rocks. There are also smooth holes in the rocks left by travelers who ground their corn meal on the rocks.
The campground is about 60 widely spaced parking places in the desert — each with a picnic table and fire ring. The campground is about half-full and very quiet.