Emerging from the lagoons of the Camargue and facing the broad expanse of the open sea stands a tall imposing edifice,
the fortified cathedral of Saint-Pierre de Maguelone. Abbot Suger of Saint-Denis who visited the site in the twelfth century described it as “A narrow island, uninhabited but for the bishop, his priests and a small retinue. It is simple, isolated and impoverished but well fortified against the attacks of the Saracens, who do not cease to infest the seas.”
Situated a short distance from the old Roman road which led from Arles to Béziers and Spain, Maguelone’s cathedral stands opposite Montpellier on the other side of the highway. Beyond, along the road lay the abbey of Saint-Thibéry towards which pilgrims to Compostela were headed.
The Guide specifies that those taking the Toulouse Road to Galicia pass via Montpellier, where there was a celebrated cult at Notre-Dame-des-Tables. 
Maguelone had no important relic cult itself, but situated as it was by the pilgrimage road between the important shrines at Les-Saintes-Maries-de-la-Mer and Saint-Thibéry it was, together with its dependent priories in the locality, a part of the supportive fabric of that particular section of the way. As the great ecclesiastical centre of the region it was an important player in the affairs of the day.
Originally, Maguelone was an island of volcanic origin set in the middle of the Melgueil lagoon, accesible only by boat until the construction in the eleventh century of a stone and wooden bridge spanning a distance over the water of one kilometre.
This small volcanic island in the midst of the Camargue was a centre of religious cult since prehistory and its origins as the seat of a bishopric go back to at least the end of the sixth century. 
After a chequered history, its period of greatest prestige coincided with the height of the Compostelan pilgrimage in the middle of the twelfth century
The cathedral and its buildings had been razed by Charles Martel in 737 in a defensive manoeuvre after the island had fallen into Saracen hands and was being used as a base for their incursions into Septimania. The inhabitants and the bishop resettled on the mainland and the see was transferred to the town of Substantion where it remained for three centuries. Maguelone was abandoned and forgotten during the period of the Carolingian renaissance in favour of the developing monastic centres at Gellone and Aniane and the growing prosperity of Montpellier. Its feudal lords, the counts of Maguelone and Melgueil resided elsewhere.
It was not until the eleventh century that Maguelone was restored to its former eminence under bishop Arnaud who had applied to Rome for assistance in rebuilding the cathedral which according to Pope John XIX, “had been reduced to nothing”. The church was rebuilt and the channel on the south side leading to the sea which had provided an easy landing point for Saracen invaders was filled in and replaced by a narrower passage facing eastwards.
In 1085, under the influence of the reforms of Pope Gregory the Great, the feudal lord of Maguelone, Count Pierre de Melgueil donated all their rights over the bishopric to Rome and thereafter the cathedral became a close ally of the Papal See. When Urban II visited on his tour of 1096, he referred to Maguelone as the second church after Rome and accorded a plenary indulgence to all who were buried on the island. A number of Popes resided as guests of the bishop, notably Calixtus II, purported author of Libri Sancti Iacobi, in 1119.
It was Pons, scion of the Megueil family who was raised to the position of one of the most powerful figures of Western Christendom, the abbacy of Cluny. Although the period of his rule from 1109 until 1122 occurred during a particularly fractious period in the history of the Burgundian monastery, Pons was actively involved in the negotiations which took place in 1120 to raise the see of Santiago de Compostela to metropolitan status.