The trans-Pyrenean footpath, the GR10, runs through it. There are several 3,000-metre summits in the vicinity, including the two highest summits, Aneto and Posets, just over the border in Spain.
There is a direct overnight train from Paris in the summer and one of the prettiest, simplest hotels in France, the Jardin des Cascades, just across the valley in the hamlet of Montauban.
We wanted to see the Lac d'Oo, the major local beauty spot. It is on the GR10, but you can dodge the first 1,000-metre climb out of town by driving up to Luchon's ski station at Superbagneres. Here, already, the world begins to look a different sort of place. Most of it is below you. At eye level there are only crags and steep pastures, all distant by a mile or more of air. We began to climb.
For the first couple of hours we made our way across grassy slopes. The afternoon was sunny and benign. On the Col de la Coume de Bourg we trod on our first patch of snow and a cold wind struck us. Suddenly, the sun was gone. Cloud settled in and it began to rain. We stopped to put on our waterproofs, but before we were done hail was rattling on our hoods. Thunder rumbled. I tried to gauge how far away it might be. Should we stay where we were or could we make it over the next ridge?
In the event, the storm never materialised and, as we began the knee- trembling descent from the last ridge, the cloud gave way to a beautiful dappled evening. The Lac d'Oo lay at our feet, a perfect green disc, fed by 300 metres of waterfall. Banks of ground-hugging rhododendron lined the path, interspersed with asphodels and blue geraniums, irises, orchids and lilies.
We were heading for the Espingo hut that overlooks its own small lake above the Lac d'Oo. Here we pitched our tent. In the mornings we performed our ablutions in the wild, cold stream where a herd of cows came down to drink, and watched the izards, jumpy as antelopes, grazing under cover of the morning mist.
We climbed to the dull, grey waters of the Lac du Portillon 600 steep and rocky metres higher up. On the way down, in the warm afternoon sun, we saw fat marmots whistling from the rocks around their burrows.
Another day we went down to the Lac d'Oo by a path so steep it felt like a stairway - an unbelievably beautiful one.
Returning to Luchon in thick mist, we went straight to the Jardin des Cascades. After a dinner of melting steak, noisette d'agneau, and fabulous desserts, we retired with delicious anticipation for our first night in a bed. Alas, the mayor had given permission for a disco in the square below. At 2am, unable to endure another beat of the massive techno- pop, we took to the woods until dawn.
We gave ourselves a day to recover and crossed into Spain. The contrast was immediate. It is partly a matter of climate, for the whole of the Spanish side of the watershed faces south, but it is also much more remote, sparsely populated and old-fashioned.
It took about three hours to drive to Eriste in the valley of Benasque, the usual starting point for the ascent of Posets, where a passable but very rough track took us up the first five kilometres of the route to the Angel Orus refuge. And thereafter the climb was magnificent, at first high in the woods above the boiling, tumbling Eriste torrent and then beside it, in open pine forest where cows grazed in the flower-strewn clearings. A stiff zigzagging climb in the last sun brought us to the refuge, full of noisy Spaniards and sober Belgians from Bruges. We dined on lentils and slept in the open beneath a magical southern night full of stars and soft breezes.
We were on our way at first light, quickly reaching the narrow snow- filled gully that gives birth to the Llardaneta stream. The snow was too hard to kick steps at this early hour and we were forced to scramble over the steep rock sides. An izard loped ahead of us with an enviable nonchalance, while two more watched us from the ridge above.
At the top, we emerged gasping in a region of red, shattered rock and blinding snow. And then, balancing along the summit ridge, glad there was no wind, we came to the broken concrete column that marks the top. There we picnicked and took each other's picture, proud to be the highest creatures between Glasgow and Granada - assuming the Sierra Nevada and neighbouring Aneto were untenanted at that precise hour. In every direction, mountains receded into the distance, for Posets, set a little way south of the main range, provides the most amazing views.
How to get there
The closest airport to Bagneres-de-Luchon is Toulouse, about 90 miles to the northeast.
Air Liberte (0345 228899) has a fare of pounds 106 return including tax.
From Toulouse, there are sporadic trains straight through to Luchon, but most journeys require a change en route to a bus.
Where to stay
The Jardin de Cascades in Montauban (00 33 61 79 83 09).
Who to ask
French Government Tourist Office, 178 Piccadilly, London W1V 0AL (0891 244123, a premium-rate number).
What to read
Tim Salmon is co-author of Rough Guide to France (pounds 10.99).Reuse content