Here's a slideshow of a walk through the abbey church at Noirlac, near Bourges, in central France. Built between 1150 and 1250 A.D., the abbey entered into decline during the 100 Years' War in the 1300s and early 1400s. At the time of the French Revolution in the late 1700s, the abbey was sold by the French government. It was used as a porcelain factory for a few decades, and then was sold back to the goverment in 1909.
Noirlac abbey was operated as a summer camp, an orphanage, and then as a hospital, and finally as a camp for refugees from the Spanish Civil War in the 1930s. The French Wikipédia article about Noirlac says that paradoxically, because the abbey was used and occupied for so many decades and centuries, it wasn't left to fall into ruin. It was the object of major restoration work between 1950 and 1980.