The abbots of the monastery soon came from the Carolingian family. The first was Hieronymus, an illegitimate son of Charles Martell, who is attested in 754 and around 775. He was succeeded by his son Fulrad, who held office in 771 and died in 826. 822/823 Hugo († 844), an illegitimate son of Emperor Charlemagne, was appointed abbot. Shortly after he took office, in 823, a new church was consecrated over the tomb, soon to be supplemented with a crypt to house the relics. Hugo was followed by Ludwig († 867), a grandson of the emperor.
The growing importance of pilgrimages and thus also of the Quentin relics made it necessary to adapt the presentation of the relics to their importance. At the end of the 12th century, the monastery chapter decided to start building a new church, which was not completed until three centuries later. Wars, epidemics and financial bottlenecks explain the unusual length of the work, which was not completed because the planned facade was never built. Stylistically, the building belongs to the Gothic style, the development of which can also be understood from it.
Source: Wikipedia