Just finished two amazing mule packing trips into the UNESCO World Heritage site, Rock Paintings of Sierra de San Francisco. The terrain is immensely rugged but the local mules were great, and sturdy on their feet. That said, I mostly walked with my camera while Nancy rode.
The impressive rock paintings are located on overhangs in the canyons.
A few of the more famous sites have board walks once you scramble up the loose rocky trails to the actual site, but we preferred the natural sites that hadn’t been altered. More photos are located at http://store.norrsell.com/Travel/Mexico/Mule-Trip-Baja-2015
A few sites are accessible during day-trips, but most sites requires a multi-day mule trip. I would highly recommend our friend Trudi with Saddling South for help for putting together a trip in the area.