The Ebro runs a long way to reach the sea, and at Mequinenza it was blocked, drowned and then reborn as a reservoir. Bco. de Campells, the ravine that shares the shelter's name, lies in the dry hills near this town in the Aragonese Bajo Cinca, where the Segre, the Cinca and the Ebro all come together in the same area. The shelter is one of the painted rock sites of the Mediterranean basin, with red figures in the Levantine style, and the setting is the sort of arid, sun-baked limestone country that gives the paintings their lasting quality.
Mequinenza has an unusual story. Coal was mined here for generations, and the town was largely rebuilt in the 1960s when the Ribarroja dam flooded the old centre. The new streets sit above the water, and the castle still looks down on the confluence of the rivers. The reservoir, now known as the Sea of Aragon, is famous with anglers who come for the giant catfish, and it has made the town a minor destination for water sports.
For the ride, the roads that wind between Mequinenza, Fraga and the small villages of the area are among the quieter in Aragon. Expect long, gentle curves along the reservoir, then climbs into scrubby hills of rosemary, juniper and pine, with occasional dust on the tarmac. Fraga, with over fourteen thousand people, is the big town for fuel, food and a bed. Mequinenza and Serós are smaller, but you can usually find coffee and a bocadillo in the bars along the main street. In summer the heat in this part of Aragon is extreme, and the wind can be strong across the open plateaus.
Spring brings green wheat and red poppies, autumn gives lovely light over the reservoir, and winter is cold but dry. Avoid midday in summer.
The shelter itself is reached on foot, and as with all rock art sites it is best to ask locally about access. The bike will be quite happy sitting at the roadside for an hour.