The Côa valley holds one of the greatest open-air galleries of Paleolithic art on earth, and it was almost lost. In the early 1990s, as work began on a dam to flood the valley, archaeologists found engravings of horses, aurochs and ibex on the schist cliffs, some of them more than twenty thousand years old. After a public campaign, the dam was abandoned in 1996, and in 1998 the site was listed by UNESCO. It remains one of the rare cases in Europe where a planned dam gave way to cave art.
Canada do Inferno, the Hell's Gorge, is one of the three main sites open to visitors, and rock engravings are on the rocks above the river Côa near its meeting with the Douro. The drawings are lines pecked and incised into the stone, sometimes layered over each other across millennia, and the animals have a fluid, lively quality. They are hard to see without a guide, because the sun must be at the right angle, so visits are by guided tour only, arranged through the Côa Museum in Vila Nova de Foz Côa, and booking ahead is wise, especially in summer. Tours often use 4x4 vehicles on rough tracks.
The country is dry, rugged and beautiful. Schist hills, terraced with almond, olive and vines, drop to the Douro, and in February the almond blossom turns the slopes white and pink. Summers here are hot, often above forty degrees, winters are cold, and spring and autumn are the best seasons. For riders, the roads are quiet and twisty, with some of Portugal's best surfaces and occasional gravel; the great Douro roads further west, such as the road from Régua to Pinhão, are a day's ride away.
Vila Nova de Foz Côa, a town of just over seven thousand, has fuel, cafés and hotels, and it is the practical base. The museum, a long concrete building dug into the hillside, is worth a visit. Local food includes roast kid and veal, olive oil, almonds and strong red wines made from the old Douro grape varieties.
Bring water and sun protection for the tour, since the valley bakes by midday.