The petrifying caves at Savonnières, three kilometres east of Villandry, are a former quarry where mineral-rich water drips slowly enough to coat anything left in it with a thin shell of calcite. The cave operators have used the process to "petrify" objects for over a century — eggs, hats, gloves, small statuettes — which are displayed at the end of the tour. The mineralised objects look exactly like themselves, only turned to stone.
The visit takes about an hour, much of it underground, and is good in any weather — particularly useful in summer when the rest of the Loire bakes. The cave keeps a steady 14 °C year-round. Open daily from April to mid-November.