DIG IT: This fall in Napa Valley, while vintners celebrated their harvests, Norman and Norah Stone toasted Stonescape: a 5,700-square-foot domed cavern cut into the side of a mountain on the couple's Calistoga, Calif., estate. It's now home to a selection of their cutting-edge art, including works by Vito Acconci and Rirkrit Tiravanija.

The Stones are familiar faces on the international modern art scene. Norman, a psychologist, is a San Francisco Museum of Modern Art trustee, and Norah, a lawyer, is involved in New York's Whitney Museum. For 17 years, they have taken counsel from Thea Westreich, a Manhattan-based art adviser, for their private collection, which also includes work by James Turrell and Cady Noland's "Log Cabin Blank" sculpture. Westreich noted that over time, the steel doors of Stonescape will rust and begin to blend in with the surrounding redwood trees on the property.

To christen the cave, the couple hosted a pair of fetes, inviting everyone from the construction workers and Brooklyn architects Martin Cox, Timothy Bade and Jane Stageberg to pals Nancy and Paul Pelosi, Kay and Sandy Walker, Vanessa and Bill Getty and John Traina and Trevor and Alexis Traina.

"The whole idea was to make the parties as casual as possible," said Norah, who one evening set the tone in a green Comme des Garçons dress over a vintage black Ungaro jumpsuit and black Prada boots. "People could swim. They couldn't wear stilettos." The next night she wore red silk Valentino pants, a vintage ribbon top, gold Miu Miu flats and contemporary gold earrings Norman bought for her in an Istanbul bazaar. Norman cut a fashionable figure as well, though he did repeat his outfit both nights: a vintage gray flannel Versace jacket with silver studs, an Issey Miyake pale pink shirt with a vertical swimmer print, Chip & Pepper jeans and silver Gucci shoes.