There is a trick to Petracos, and it is to look at the walls in the order that the rock gives them to you. The eighth shelter is at one end of the plateau, where the cliff curves and the shade falls early, and what you notice first is not paint at all, but the way the rock has weathered into smooth bowls and thin ledges. Water has done this over thousands of years, and the painters used the hollows that it made. Without the erosion there would be no shelters, and without the shelters no art, and the whole thing is a kind of collaboration between stone and people.
Four kilometres from Castell de Castells, the plateau sits at the head of a valley that has seen a great deal. In 1609 it was almost emptied of its Morisco inhabitants, and the farms and terraces were rebuilt by newcomers over the next decades. Later, in the nineteenth and twentieth centuries, the villages shrank again as people moved to the coast and the factory towns, and today the area is quiet and half-forgotten, which is why the paintings survive.
Ride up from Callosa d'en Sarrià, through the almond and olive terraces, and enjoy the shape of the road: tight at first, then rolling, with the sea behind you and the Serrella ahead. The surface is generally good, although a few patches of tarmac are broken and some corners carry gravel. In winter, mornings can be icy. For fuel, Pego, eleven kilometres off, is the place, with a supermarket and bars, and Murla and Vall d'Ebo are tiny.
Look after the shelters. Keep to the paths, do not climb on the rock, and carry water, because the plateau offers little shade. A good pair of boots and a hat will make the visit much more comfortable.