The wealth and influence of the abbey extended to many daughter foundations, including St. Michael's Mount in Cornwall. However, its popularity and prestige as a centre of pilgrimage waned with the Reformation, and by the time of the French Revolution there were scarcely any monks in residence. The abbey was closed and converted into a prison, initially to hold clerical opponents of the republican regime. High-profile political prisoners followed, but by 1836, influential figures—including Victor Hugo—had launched a campaign to restore what was seen as a national architectural treasure. The prison was finally closed in 1863. In 1872, the highly decorated French architect of historic monuments, , was responsible for assessing the condition of the Mont. It took him about two years to convince his minister to classify Mont Saint-Michel a historic monument, and it was officially declared as such in 1874. From then on, this highly qualified and educated architect, member of the Academy of Fine Arts, devoted himself entirely to the restoration of "la Merveille". Under his direction, gigantic works were undertaken, starting with the most urgent.