That puts it in the gap between the last decent town and the first real mountains, where fields of almond and olive trees give way to oak, box and rock. The shelters here belong to the Levantine tradition, small figures in red pigment made by hunter-gatherers and early farmers, and the whole group is listed by UNESCO as part of the Mediterranean rock art of the peninsula.
The honest truth is that most of these overhangs are not signposted for the casual passer-by, and they are not the kind of place you ride up to and photograph from the seat. The paintings are fragile, and some are on protected ground with limited access. What the ride gives you is the setting: the approach to the Sierra de Guara from the south, with the Pyrenees faintly visible to the north on a clear winter day and the plateau of the Somontano below.
From Barbastro the road narrows quickly after the last roundabout. You wind up through low hills, over short rises, past little farms with big stone barns, and then drop into the Vero canyon. The bends are medium in size, the surface is mostly good, and the places where it breaks up are usually the places where a stream crosses. There are few barriers, so keep your speed honest on blind left-handers. In summer you want to start early, because the rock radiates heat in the afternoon, while in March the almond blossom brings a pale pink flush to the lower terraces.
People have lived off this country for a very long time. Before the shepherds came, someone had cause to climb into these overhangs and paint on them, and thousands of years later the local people still talk about the Moors who were supposedly the painters, a folk tale that has produced a good many cave names. Fill the tank in Barbastro before you set off, since the villages along the valley are small and pumps are scarce, and carry a bottle of water if you plan to walk.