Pontino / Alamy

Mont Sainte-Odile, France

18 of 20

When ancient books began disappearing from this seventh-century monastery in France’s remote Vosges Mountains, speculation—even among the police—naturally turned to possible secret entrances. That line of thinking was vindicated when a bookcase swung open and exposed a forgotten medieval passageway with rope ladders leading to the roof and public areas. The thief turned out to be a local teacher who spied the hidden space on an old map and couldn’t resist investigating. Mystery solved—for the moment.

Kelsi Maree Borland

World's Most Mysterious Buildings

Mont Sainte-Odile, France

When ancient books began disappearing from this seventh-century monastery in France’s remote Vosges Mountains, speculation—even among the police—naturally turned to possible secret entrances. That line of thinking was vindicated when a bookcase swung open and exposed a forgotten medieval passageway with rope ladders leading to the roof and public areas. The thief turned out to be a local teacher who spied the hidden space on an old map and couldn’t resist investigating. Mystery solved—for the moment.

Kelsi Maree Borland

Pontino / Alamy

World's Most Mysterious Buildings

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