There is a shelter near Alquézar that people call Mallata, and a ravine of the same name, and on a summer weekend you could miss both while looking for a parking space. The Barranco de la Mallata is a narrow side-canyon of the Vero, a few kilometres from Alquézar, and it holds shelters that have become famous among specialists for their Levantine paintings. Mallata B1 is one of them, a small, shaded hollow where the paint has survived better than you might expect.
From Alquézar the road runs up the Vero valley to Colungo, a small village that has an interpretive centre for the rock art of the canyon, and this is the best place to start, because it explains the sites you cannot visit and tells you which are open. The road is narrow, winding and well surfaced, with bends that hug the hillside and views over the river, and it is lightly trafficked outside the school holidays. On a clear spring morning it is one of the best short rides in Aragon.
Alquézar's Collegiate Church overlooks the gorge, and below it the footpaths along the river are a pleasure for a stroll. The village has plenty of terraces, and local products include olive oil, honey and the wines of the Somontano. Barbastro, twenty-one kilometres away, has the fuel, as do larger villages on the plain. Salas Altas and Angüés have bars, but little else.
Treat the paintings with care. Do not wet them or touch them, and follow the instructions of the park staff. A little water makes the pigment glow for a moment and does lasting harm, and people have done it in good faith for generations, which is part of why so many panels are now behind grilles.
The light matters more than anything else you can control. The ravine runs between tall walls, so a shelter that is bright at ten can be in shade by two, and a photograph taken in flat midday glare shows almost nothing. Take your time, let your eyes adjust, and look for the faint orange line before you look for the figure. Dress for a walk, not a ride, because the paths from the road are rough, and keep an eye on the weather in the Guara, where storms build quickly over the ridges in late summer.