Ordesa y Monte Perdido National Park

Listen for a moment. Under the trees, you can hear the Arazas river before you can see it. The water runs over pale stone, and the air is cool, even on a summer morning. Above you, the walls of the valley rise in bands of grey, ochre and rust. They catch the sun long before the valley floor does. This is the Ordesa valley, high in the Pyrenees of Aragon, and you are standing at the bottom of one of the deepest limestone canyons in Europe.

Welcome to Ordesa y Monte Perdido National Park. It sits in the province of Huesca, in northern Spain, against the border with France. The park joins four main valleys: Ordesa, Añisclo, Escuaín and Pineta. Each one runs out from the same great limestone massif. At its centre stands Monte Perdido, the Lost Mountain. At about 3,355 metres, it is one of the highest summits in the whole Pyrenean range. It is also the highest limestone massif in Western Europe.

Here is the first thing most visitors do not know. This place is one of the oldest protected landscapes in Spain. Ordesa was declared a national park in 1918, in the same year as Covadonga in Asturias. These were the country's first two national parks. At first, the protected area covered only the Ordesa valley itself. In 1982 the park grew to include the other valleys and the Monte Perdido massif, and it took the longer name you see on the signs today.

The international world took notice too. In 1997, UNESCO listed the area as a World Heritage Site, under the name Pyrenees, Mont Perdu. The listing crosses the border. It joins this Spanish side with the French cirques of Gavarnie and Troumouse on the far side of the mountains. UNESCO recognised the landscape for its geology, but also for its people. Shepherds have moved flocks across these high passes for centuries, and their way of life shaped the meadows.

Now look again at those canyon walls. The rock is mostly limestone, laid down long ago at the bottom of an ancient sea. Later, the collision of continents pushed this seabed up into mountains. Then ice did the carving. Glaciers ground the Ordesa valley into its broad U shape. On the higher ground, you can find fossils of sea creatures in the stone. It is a strange thought — to stand above two thousand metres and find shells.

The classic walk here follows the valley floor to the Cola de Caballo, the Horsetail waterfall. The path starts at the meadow known as the Pradera de Ordesa. It climbs gently through forest, then opens out into the high, bright part of the valley. Along the way, the river drops over a series of falls. Watch for the Gradas de Soaso, the Soaso Steps. There, the water spills over stone ledges like a wide staircase.

The forest along the lower path changes as you climb. Near the river, you walk under beech trees, with their smooth grey bark. Higher up, silver fir and pine take over. In autumn, the beech leaves turn copper and gold against the dark conifers. The ground under the trees is often damp and soft. Moss covers the boulders. On a quiet day, the loudest sounds are water, wind in the needles, and your own footsteps.

Look up, often. The cliffs are home to some of Europe's great birds. The bearded vulture, known in Spain as the quebrantahuesos, the bone-breaker, nests in these mountains. It feeds largely on bone. It carries bones into the air and drops them onto rocks to split them open. You may also see griffon vultures circling in slow loops, and golden eagles. In the high meadows, listen for the sharp whistle of marmots.

Here is the second surprise, and it is a sad one. This park was the last home of the bucardo, the Pyrenean ibex. This wild mountain goat once lived across the range. By the end of the twentieth century, only a handful remained here. The last known female died in 2000, and the subspecies was declared extinct. In 2003, scientists created a clone from her preserved cells. The kid was born alive, but it lived only a few minutes. It is often described as the first animal to be brought back from extinction... however briefly.

High above the valley, on the French border, there is a gap in the ridge called the Brecha de Rolando, Roland's Breach. It is a tall, square notch cut through a wall of rock. Legend has it that Roland, a knight in the medieval stories about Charlemagne, made it himself. According to the tale, he struck the mountain with his sword while trying to break the blade before his death. Geologists explain it as erosion. The legend is better company on the climb.

Monte Perdido itself still holds a small glacier on its northern face. Like many glaciers in the Pyrenees, it has shrunk a great deal in recent decades. Scientists study it closely as a measure of a warming climate. From the valley, you will not see much of the ice. But on clear days, the summit appears at the head of the valley, pale and quiet above the rest.

A few practical notes. The village of Torla, just outside the park, is the usual gateway to the Ordesa valley. In the busy seasons, access for private cars is restricted, and visitors ride a shuttle bus into the valley. Weather changes fast in these mountains. A bright morning can turn into a storm by afternoon. Carry layers, water and a map, and stay on marked trails. The meadows and the animals are fragile.

Before you move on, stop where you are and take one more look. Notice the bands in the rock, laid down one on top of another, like pages in a closed book. Notice the colour of the river — clear over the pale stone, green in the deeper pools. Then listen once more for the water. It was here before the first shepherds, and before the park. And as you walk away, it will keep running through the valley.