Church of l’Hôpital Saint-Blaise

In the village of l’Hôpital Saint-Blaise, which is located on one of the routes that linked France to Santiago de Compostela, there's a twelfth-century Romanesque church with a series of curious Hispano-Arab elements. The church was once part of a hospital complex built by the canons of the Abbaye Sainte-Christine du Somport to accommodate and provide care for pilgrims. 

The church contains many references to the East. The nave and transept intersect in the centre to form a Greek cross on the floor. An eight-sided tower rises from the point at which they meet. The windows, which are decorated with very simple pierced stone slabs, seem to pay tribute to the marble grilled windows in the mosques of Damascus and Córdoba. The openings in the apse and tower are crowned by poly-lobed arches. The bonds of the walls, the hollowing out of the pier corners, and the corbelling out of certain transverse ribs seem to imitate brick construction techniques, with which Muslims were very familiar.

However, the small dome mounted on ribs, which has been constructed in the supporting structure of the central tower, is the most direct legacy of Muslim architecture. The dome’s vault is supported by sixteen ribs that intersect away from the centre by forming an eight-pointed star. The centre, which has been left bare, forms an octagon without ornamentation. The oldest examples of this type of construction are found in Córdoba, in the four sumptuous domes constructed circa 963 on the orders of caliph al-Hakam II: the dome of the Villaviciosa Chapel and the domes that precede the mihrāb. No other such constructions were built anywhere else at that time[1]. The architects in the caliphal period probably invented this process, which enabled them to strengthen the structure of the vault, while giving the central area a sophisticated outline. The process spread from Córdoba and became widespread.

The process was used again in the small Bab al-Mardum Mosque in Toledo (circa AD 1000), which later became the Church of Santo Cristo de la Luz; and was then used in the prayer room in the Casa de Las Tornerías (circa 1036). In the Reyes de Taifas era, the oratory in Aljaferia palace in Zaragoza (end of the eleventh century) was crowned by an imposing ribbed dome. Under the Almoravids (1056–1147), this type of construction spread to North Africa. It is found in the Great Mosque of Tlemcen in Algeria (1082–1136) and the Qarawīyīn Mosque in Fès (circa 1135).

Outside the Islamic sphere, which subsequently showed a preference for structures with muqarnas, the ribbed dome, which was probably transmitted by itinerant Mozarabic workshops, spread to Christian Spain, particularly Castile and Aragon. It is found in the chapel of the Cistercian Huelgas Convent in Burgos, and in the octagonal chapel of Torres del Río in Navarre. And it’s found in various other places. The small Church of l’Hôpital Saint-Blaise, on the northern side of the Pyrenees, is the most advanced point of its diffusion.

During the Gothic period, this construction technique continued to be used in Spain, even though Islamic references were no longer visible. It led Spanish Renaissance architects to increase the number of cimborios: ribbed domes containing in their centre a small lantern-turret lit by lateral windows.

The last known example dates from the seventeenth century and is found in the Church of San Lorenzo in Turin, Italy. It’s a magnificent lantern-turret mounted on intertwined arches, which was designed and constructed by the architect and Jesuit Father Guarini after a study tour in Spain.