Of a defensive nature and perched on the top of a steep, rocky hill, it served as the residence of the bishops of Sion.

The stones of the castle were used for some time for construction in the region before the ruins were reinforced in the 19th century to make it a historical monument.

[5] In 1994, excavations on the plateau east of the Tourbillon Castle revealed a Neolithic dwelling dated to the fifth millennium BC.

In the nineteenth century, historians claimed that a Roman tower occupied the top of Tourbillon Hill before the construction of the castle.

However, in the late 10th century the last King of Upper Burgundy Rudolph III, granted the County of Valais to Bishop Hugo (998–1017).

By the 12th century they began building impressive churches and castles in Sion to represent their power and administer their estates.

In the 12th century the Cathedral Notre Dame de Sion (du Glarier) was built in the town below Valère hill.

[8] The construction of Tourbillon castle is most probably linked to a major project to improve the fortifications of the town of Sion between the thirteenth and fourteenth centuries.

He imitated other members of his family, who had castles built in the Aosta Valley to strengthen their power on several occasions.

[9] Several deeds signed in Tourbillon as early as May 1307 show that the habitable parts of the castle were completed when Boniface died on 13 June 1308.

After Tavelli bought Majorie Castle in 1373, Tourbillon became a temporary residence for the bishop but retained its military importance.

A third conflict, this time with a nobleman from the Upper Valais named Pierre de la Tour, broke out in 1352 when he wanted to emancipate the bishop.

[11] This did not prevent new revolts, which were violently punished by Amédée VI; he ordered the town of Sion to be pillaged and partially burnt down.

[13] In March 1361, after nine years as bailiff, Amédée VI signed the Treaty of Evian and gave up interfering in the affairs of the bishop of Sion.

Amedeus VII, a relative of Édouard de Savoie, laid siege to Sion and partially destroyed the town.

Once the revolt had been brought under control, he imposed a severe peace treaty on the rebels allowing the bishop to recover his castles.

[17] Between the resignation of Édouard de Savoie-Achaïe and the election of the new bishop, the Count of Savoy made men available to guard the castle.

The population then organised such a huge uprising that William II fled to the Soie Castle and Witschard went to Bern to seek help.

[20] The castle of Tourbillon was in a pitiful state; its interiors and roofs were totally destroyed by fire and its walls were cracked in many places.

[21] In 1418, André dei Benzi de Gualdo was appointed administrator of the diocese of Sion before becoming bishop in 1431 on the death of William II, who remained in Bern.

He quickly ordered the reconstruction of La Majorie, but left the renovation of Tourbillon for later, while ensuring that its walls did not collapse.

[27] The various conflicts affecting the Valais finally left the bishopric of Sion without the resources needed to finance the work, and Tourbillon remained in ruins.

In 1963, a Pro Tourbillon association was created and, two years later, the Swiss League for National Heritage organised the sale of a gold shield which enabled consolidation work to begin.

The western access is cut off by a fortification wall, equipped with a gate, which was most certainly overhung by a bypass, as the remaining machicolations and merlons suggest.

The large main tower is similar to a dungeon and is divided into two parts: the bishop's flats to the east and a reception room to the west.

The tower included the bishop's room, which can be located thanks to a large window on the south side, and traces of a chimney remain, although it seems to have disappeared during the reconstruction of the 15th century.

[47] The chapel of Tourbillon Castle, dedicated to Saint George, is located to the south-east of the enclosure and consists of two bays; the one accessible from the north-west serves as the nave.

[51] The paintings in the first cycle depict various scenes, such as the Annunciation, the Crucifixion of Jesus of Nazareth or Saint George slaying a dragon.