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Caves of Mount St. Peter  – For centuries marl, a calcareous clay was excavated for building purposes. Eventually, an underground labyrinth of over 2,000 passages evolved. It is estimated that the total distance of these passages adds up to 200 km with certain sections as high as 16 meters. Historically, these caves, mainly served as a place of refuge during sieges and wars.
Till this very date, one can see on some walls signs, writings and drawings which narrate the history of these caves.

Names, dates and hometowns were scratched on walls by American soldiers during world war II.
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