Introduction
Welcome to a walk that climbs into the sky above the Rhone Valley. This tour focuses exclusively on the two extraordinary hills that define Sion's skyline: the fortified basilica of Valere to the south and the ruined castle of Tourbillon to the north. Together, they create one of the most dramatic urban silhouettes in Switzerland, two rocky sentinels rising 120 metres above the valley floor, each crowned with medieval fortifications that have watched over this crossroads for nearly a thousand years.
This is not an easy walk. The paths are steep, the terrain is rocky in places, and in summer the exposed hillsides can be scorching. But the rewards are extraordinary: a church that houses the oldest playable organ in the world, a romantic ruin that looks like a painting by Caspar David Friedrich, panoramic views that sweep from the Bernese Alps to the peaks of the Pennine chain, and a unique natural environment where Mediterranean-like steppe vegetation clings to sun-baked slopes in the heart of the Alps.
The two hills are geologically distinct from the flat valley floor around them. They are outcrops of harder rock, ancient reef limestone that resisted the erosion that carved the Rhone Valley into its present broad, flat-bottomed form. While the surrounding softer rock was ground away by glaciers and rivers over millions of years, these two knobs of resistant stone remained, perfectly positioned for the defensive structures that medieval builders would place upon them.
Stop 1: Rue des Chateaux Trailhead — 46.2340, 7.3620
Begin at the foot of the Rue des Chateaux, where the cobbled lane begins its steep ascent between the two hills. A signpost marks the paths to both Valere and Tourbillon. We will visit Valere first, as it offers the richer interior experience and is best seen before fatigue sets in.
Before you climb, look at the vegetation on the hillside. You will notice immediately that this is not typical Swiss greenery. The slopes are covered with dry grassland, thorny shrubs, and plants that look as if they belong in southern France or even North Africa. This is the famous Sion steppe, one of the most botanically remarkable habitats in Switzerland.
The Rhone Valley around Sion receives less than 600 millimetres of rainfall per year, making it the driest place in the country. The south-facing slopes of these hills receive even less moisture and can reach surface temperatures of over 60 degrees Celsius in summer. In this extreme microclimate, plants from the Mediterranean and Eurasian steppes have found a refuge that exists nowhere else in the Alps. You may see the feather grass Stipa pennata, whose silky plumes wave in the breeze, the silver-leaved Artemisia vallesiaca, endemic to the Valais, and in spring the delicate purple flowers of the Tulipa australis, a wild tulip species.
The insect life is equally remarkable. Several species of butterfly and grasshopper found here exist at the northern limit of their range, surviving only because of this exceptional microclimate. Conservation efforts in recent decades have protected these hillsides from development, recognising their status as one of the most important dry grassland sites in central Europe.
Stop 2: The Ascent to Valere — 46.2339, 7.3638
The path climbs steeply through terraces that were once vineyards. Wine has been grown on these slopes for at least two thousand years. The Romans cultivated grapes here, and medieval records show that the Bishop of Sion maintained extensive vineyards on the lower slopes of both hills. Today, some small parcels of vines still cling to the terraces, producing tiny quantities of wine from indigenous Valais varieties.
As you climb, the views begin to open up. To the west, the Rhone Valley stretches toward Martigny and the great bend where the river turns north toward Lake Geneva. To the east, the valley runs straight and wide toward Visp and the high Valais. The flat valley floor below you is intensively farmed, with orchards of apricots, pears, and apples interspersed with vegetable plots and the characteristic asparagus fields of the Valais.
The terracing of these hillsides is itself a remarkable feat of engineering. The dry stone walls that support each level were built over centuries by hand, without mortar, using stones cleared from the thin soil. This technique, known as murgering in the local dialect, is now recognised as intangible cultural heritage. Each wall is slightly battered, meaning it leans back into the hillside, and the gaps between the stones provide habitat for lizards, snakes, and countless invertebrates.
Pause and catch your breath. The steepest section is behind you. The walls of the Valere basilica complex are now visible above, their grey stone blending into the cliff face from which they seem to grow organically.
Stop 3: Valere Basilica Exterior — 46.2336, 7.3652
You have reached the fortified enclosure of Valere. The complex before you is not simply a church but a complete fortified settlement, a castle-church hybrid that was the residence and stronghold of the canons of the Cathedral Chapter of Sion for nearly eight hundred years.
The earliest structures on this hilltop date from the eleventh century, though the basilica in its present form was built primarily in the twelfth and thirteenth centuries. The canons who lived here were not monks but secular clergy, priests who served the cathedral but lived according to a common rule. They were powerful men, often from noble families, and their hilltop fortress reflected both their spiritual authority and their temporal power.
Look at the fortification walls. They are massive, up to three metres thick in places, with crenellations and arrow slits that show this was a place built for defense as well as worship. The canons of Valere did not always live in peace. The Valais was a turbulent region throughout the Middle Ages, with frequent conflicts between the bishop, the local nobility, and the communes. Valere was besieged on several occasions, and its defenses were tested in earnest.
The approach to the basilica entrance takes you through a series of courtyards and gatehouses, each one a further layer of security. The residential buildings of the canons, now partly ruined, flank the approach. Some rooms have been restored and house the Museum of History, part of the Valais Museum network, which displays artefacts from the cathedral treasury, medieval arms and armour, and carved wooden chests.
Stop 4: Inside the Basilica — 46.2335, 7.3654
Step through the heavy wooden doors into the nave of the basilica, and you enter one of the most remarkable sacred spaces in Switzerland. The interior is dim, lit by small Romanesque windows, and the air is cool even on the hottest summer days. The walls are covered with fragments of medieval frescoes, their colours faded but still vivid enough to discern scenes from the lives of saints and episodes from the Passion of Christ.
The frescoes date from the thirteenth to the fifteenth centuries and represent successive campaigns of decoration. The earliest are in the Romanesque style, with stiff, hieratic figures and flat gold backgrounds. Later paintings show the influence of the International Gothic style, with more naturalistic figures and richer colour palettes. Together, they form one of the most important cycles of medieval wall painting in the Alps.
The choir stalls are another highlight. Carved in the late fifteenth century, they feature misericords, the small carved shelves on the underside of the folding seats, decorated with scenes of daily life, mythical creatures, and satirical images that contrast strikingly with the religious solemnity of the setting. Look for the figure of a fox preaching to a congregation of geese, a common medieval satire on corrupt clergy.
But the supreme treasure of Valere is the organ. Located in a gallery on the south wall of the nave, this instrument dates from approximately 1435 and is the oldest playable organ in the world. The wooden case is Gothic, with painted panels depicting the Annunciation. The pipes, many of them original, produce a sound that is hauntingly different from a modern organ: thinner, more reedy, with an immediacy and presence that modern instruments, for all their power, cannot replicate.
Concerts on the Valere organ are held regularly throughout the summer as part of the International Organ Festival. Hearing this instrument fill the ancient nave with music composed in its own era is an experience of profound historical and emotional power.
Stop 5: Valere Rampart Viewpoint — 46.2332, 7.3659
Exit the basilica and walk to the eastern rampart of the fortification. Here, on the highest point of the Valere hill, you have a panorama that encompasses the entire central Valais.
To the south, beyond the valley floor, the mountains of the Pennine Alps rise in a wall of rock and ice. On a clear day, you can identify the Weisshorn, a perfect pyramid of snow and ice at 4,506 metres, and the distant peak of the Matterhorn, just visible to the far south. The Pennine chain contains some of the highest mountains in the Alps and forms the border between Switzerland and Italy.
Directly below you, the old town of Sion is spread across the saddle between the two hills. The rooftops are a patchwork of orange tile and grey slate, punctuated by church towers and the occasional modern intrusion. The Rhone River, tamed by embankments and channels, flows through the valley floor in a straight line. Before the river corrections of the nineteenth century, the Rhone was a wild, braided river that flooded regularly, making the valley floor a marshy, malaria-plagued wasteland. The engineering works that confined the river and drained the marshes transformed the Valais into the agricultural powerhouse it is today.
To the north, directly across from you, Tourbillon Castle sits on its rocky throne. The ruin looks spectacular from this angle, its broken walls and empty windows framing the sky. We will visit it next, but first, absorb this view. You are standing on a promontory that has been occupied for at least three thousand years, and the panorama has changed remarkably little in that time.
Stop 6: The Saddle Between the Hills — 46.2340, 7.3665
Descend from Valere by the main path and cross through the saddle between the two hills. This low point between Valere and Tourbillon was the site of the medieval bishops' residence and the original settlement of Sion. The Old Town streets that wind through this area follow routes that have been in continuous use for centuries.
The saddle is also where the two cultures of Sion's hills meet. Valere was the domain of the Cathedral Chapter, the college of canons who administered the diocese. Tourbillon was the personal fortress of the Bishop, the prince of the Valais. The relationship between these two powers was often tense, and the physical separation of their residences on opposite hilltops reflects a deliberate division of authority.
As you cross the saddle, look for the small vineyard plots that occupy the sunny terraces between the paths. These tiny parcels produce Fendant, the Valais name for Chasselas wine, and Petite Arvine, an indigenous variety that is one of the great white wines of the Alps. The grapes ripen to extraordinary sweetness on these sun-baked slopes, and the resulting wines have a mineral intensity that reflects the geological character of the soil.
The path to Tourbillon begins its ascent from the eastern end of the saddle. A wooden signpost marks the way.
Stop 7: Tourbillon Ascent and Steppe Ecology — 46.2345, 7.3678
The climb to Tourbillon is steeper and more exposed than the ascent to Valere. The path switchbacks up the rocky southern face of the hill, passing through some of the finest steppe grassland in the Valais. In spring, this slope is a tapestry of wildflowers. In summer, it shimmers with heat, and the only sounds are the buzz of insects and the distant hum of traffic on the valley floor.
This is one of the best places in Switzerland to observe the dry grassland ecosystem known as the Felsensteppe, or rock steppe. The thin soil, extreme heat, and minimal rainfall create conditions that favour plants adapted to drought and exposure. The dominant grass is Stipa capillata, whose feathery seed heads form silvery waves across the slope. Among the grasses, look for the pink flowers of Dianthus sylvestris, the wood pink, and the bright yellow of Hippocrepis comosa, the horseshoe vetch.
Reptiles thrive here too. The green lizard, Lacerta bilineata, which can reach 40 centimetres in length, basks on the warm rocks. The Aesculapian snake, a large, non-venomous species, hunts among the stone walls. And in the crevices of the rock, the scorpion Euscorpius germanus may be found, one of only two scorpion species native to Switzerland, a relic of warmer climatic periods.
The exposed rock along the path is limestone, formed from the compressed shells of marine organisms in a warm, shallow sea roughly 150 million years ago during the Jurassic period. Fossils are occasionally visible in the rock face, though they are protected and should not be disturbed.
Stop 8: Tourbillon Castle — 46.2348, 7.3695
You have reached the summit of Tourbillon, and the ruined castle spreads before you. Built in 1294 by Bishop Boniface de Challant, Tourbillon served as the personal residence and stronghold of the Bishops of Sion for nearly five hundred years. It was a place of considerable luxury as well as defensive strength: the bishops held court here, received ambassadors, administered justice, and plotted the political manoeuvres that maintained their power in the turbulent Valais.
The castle was damaged by fire in 1373, rebuilt, damaged again in various conflicts, and finally destroyed by a catastrophic fire on May 24, 1788. A fire that had broken out in the town below spread uphill, driven by the strong valley winds, and engulfed the castle. The flames were so intense that the stone walls cracked and the lead from the roof melted. The Bishop and his household barely escaped. The castle was never rebuilt, and its ruins have stood open to the sky ever since.
Walk through the shattered gateway and into the main courtyard. The walls still stand to a considerable height, and the outline of rooms, corridors, and staircases is clearly legible. The chapel of St. George, in the northeast corner, is the best-preserved interior space. Its walls retain fragments of frescoes from the fourteenth century, including a depiction of St. George slaying the dragon that retains some of its original colour.
Stand at the eastern wall and look out. The view from Tourbillon is arguably the finest in the Valais. The entire valley is laid out before you, from the vineyards of Savièse to the west to the industrial town of Visp in the east. The Alps rise on both sides, and the sense of being perched on a natural watchtower is overwhelming. You can understand immediately why every power that controlled this valley placed a fortress on this exact spot.
Conclusion
The twin castles of Sion offer one of the most rewarding walks in Switzerland for those willing to make the climb. You have visited a fortified church that houses a treasure of medieval art and the oldest playable organ in the world. You have crossed a landscape of extraordinary botanical richness. And you have stood in the romantic ruins of a prince-bishop's castle, surrounded by one of the great Alpine panoramas.
Descend by the same path and return to the old town. A glass of Fendant or Petite Arvine on the terrace of one of the Rue du Grand-Pont cafes is the traditional reward for this climb. You have earned it.
Practical Information
- Best Time: Morning or late afternoon. Avoid the midday heat in summer, as the exposed hillsides can reach extreme temperatures. Spring is ideal for wildflowers.
- Wear: Sturdy hiking shoes with good grip. The paths are rocky and steep in places. A sun hat is essential in summer.
- Bring: At least one litre of water per person. There are no facilities on the hilltops. Sunscreen and sunglasses.
- Nearby Food: The old town of Sion has excellent restaurants. Try a raclette or a plate of local dried meat (viande sechee) paired with a Fendant from the surrounding vineyards.
- Access: Valere is open year-round. The basilica interior has limited opening hours. The Tourbillon ruins are open April to November, weather permitting. Check locally for current hours.