The Río Martín is a modest stream that has done something dramatic. Over a very long time, it has cut a deep, narrow gorge through the pale limestone of the Bajo Aragón, with walls that crowd in on either side, and the stretch the locals call Los Estrechos, the Narrows, is where the cleft is tightest. The shelter at Los Estrechos II lies about five kilometres from Albalate del Arzobispo, and is one of the sites along the river protected by a cultural park. It carries painting in the Levantine tradition, protected by UNESCO as part of the rock art of the Mediterranean basin in Spain, and the ride links it to the Abrigo de la Higuera, the Fig-Tree Shelter.
It is easy to see why people painted here. The gorge offers shade in summer, shelter from the wind, water and a corridor along which animals move. Red and yellow bands of rock show in the cliffs, and in the right light, the walls glow. Swifts and swallows nest in the cracks, and vultures glide above the rim. In the river itself, reeds and poplars line the banks.
Riding in this area is relaxed. The main roads are fast and straight, crossing the dry plateau, and the lanes along the gorge are narrower, with bends and good views, though some stretches are rough. Traffic is light. The Cierzo, the cold wind of the Ebro basin, blows often and hard, and can make riding on open stretches tiring. In summer, the heat is fierce and shade is rare. Spring and autumn are best.
Albalate has about two thousand people and several stations, so fuel is easy. Híjar, about thirteen kilometres away, is a historic town with a well-preserved old Jewish quarter and a long tradition of drum processions at Easter. Andorra, a larger town of nearly eight thousand people, is another option. Ariño, a mining town, lies close by. Carry water, and give yourself time to look at the gorge from the road.