Grotte de la Tante Airie, Natural cave in Pierrefontaine-lès-Blamont, France.

Grotte de la Tante Airie is a natural cave in the Jura Mountains featuring large limestone formations carved by flowing water. Its passages display mineral deposits and showcase how water has gradually sculpted the rock over time.

The cave formed millions of years ago through water erosion of limestone. Archaeological discoveries inside show that people occupied this site during prehistoric times.

The name refers to Tante Airie, a figure of local lore in the Blamont area associated with the Christmas season. She is remembered as a gift-bringer, a role tied to the older figure of Aunt Arie honoured in regional tales of the Franche-Comté.

You can reach the cave via a marked trail of about 5 kilometers starting from behind the retirement home in Pierrefontaine-lès-Blamont. Parking is available near the trailhead.

The Creuse stream runs through the cave and has hollowed out a series of rock basins along its bed. Each basin holds water and shows a different surface of limestone, from smooth, rounded hollows to rougher, pitted walls. Visitors can follow the stream's course and see where the water still works on the rock.