Restrain the urge to enter or climb on their stone walls. Walk carefully around the slopes that support these structures. Ruins are best observed from a distance with the aid of binoculars. That way you will reduce your impact to zero. Areas with ruins are essentially outdoor museums, and visitors should conduct themselves as they would in any museum displaying irreplaceable artifacts.
Ruins are an interesting highlight of a hike, but are inappropriate places to make camp.
After observing an archaeological site, move on before having meals. Food crumbs and garbage may attract rodents that could then nest in the site. Pigments of ancient pictographs are easily destroyed by skin oils. Restrain the urge to touch them, particularly hand-print pictographs. Never add your own graffiti to irreplaceable rock art panels.