Get Roth Martin and his business partner, Steven Volpe, talking about the objects in the pied-à-terre they share in Paris, and the stories come out thick and fast. Consider the Irving Penn photograph of a dead mouse, which was bought from the estate of Richard Avedon. Penn’s wife, Lisa Fonssagrives, the original supermodel, spotted the expired rodent on a street of the French capital. "She picked it up with her American Express card, wrapped it in a scrap of newspaper, and took it back to New York," Volpe recounts. Then there is the formidable granite sculpture by Dominique Stroobant. Its official title is Freccia, but its present owners call it the Toe Breaker. As Martin explains with a pained laugh, "The first day it was installed, I woke in the middle of the night and walked straight into it."

Partners in Hedge, a San Francisco gallery of 20th-century furniture and decorative arts, the pair has made regular buying trips to Paris ever since Martin, a former biotech executive, enlisted Volpe—a designer with a top-notch Bay City clientele—to decorate his house a few years ago. Before long, the two gentlemen had joined professional forces. "We were spending so much time here, in and out of hotels," Martin says, "that it made sense to buy a flat." They found one in the 7th arrondissement, in a prime location just steps from the Eiffel Tower. It is a quintessentially Parisian space, with boiserie, parquet, and a marble fireplace, and the three bedrooms are perfect for when Martin’s wife, Emily, and their two-year-old son, Harry, come to town. The place also is big enough to handle the three dogs that are occasionally in transatlantic tow.

A gelatin-silver photogram by Adam Fuss and
19th-century École des Beaux-Arts student
drawings of floor patterns in the back hall.

The apartment may be roomy, but its space has been judiciously used. One section of the back hall is now an ad hoc library with floor-to-ceiling bookshelves, and a 1950s Gilbert Poillerat drop-leaf dining table is ensconced in the entrance hall. "There’s usually just the two of us here, so it works pretty well," Martin remarks. It also serves as a games table and can easily be moved into what is now a double living room in the event of a dinner party. A neutral palette of grays and whites keeps the residents’ collection of furnishings and art front and center. Volpe and Martin share a taste for midcentury French and Italian designs, including furniture made by Jansen, the Paris firm patronized by everyone from the Belgian royal family to Jacqueline Kennedy. One of its lacquered Egyptian-style tripod stools stands in the living room. "There was a quality, a workmanship, a level of detail that was just really intriguing," declares Volpe of the company. Other well-known names are represented too: wardrobes by André Sornay, a lamp by Marc du Plantier, vintage fabric with Picasso designs, and a trio of small, whimsical Diego Giacometti sculptures.

More than anything, however, the apartment’s inhabitants are drawn to what’s cool but offbeat, like the Nuage cocktail table, a circa-1970 Plexiglas-and-steel design by the aristocrat-artist Guy de Rougemont. As Martin explains, "We like noniconic pieces that provoke a reaction." Perhaps the most striking acquisitions are a chair and stools by the Italian design team of Luciano Grassi, Sergio Conti, and Marisa Forlani. "They are surprisingly comfortable," says Volpe of the suite, its transparent nylon-mesh upholstery seemingly spun by industrious spiders. "You can sit on them all night."

An appreciation for the unusual has led Volpe to deploy a number of arresting visual tricks. Beds are surmounted by one great object set dramatically off-center, such as a Line Vautrin starburst mirror or a pencil portrait of the American style diva Babe Paley. "Breaking the rules often gives a room charm and makes it less stagnant," the designer says. In the living room, the television screen is mounted on a stainless-steel pole, ready for little Harry Martin and the latest Baby Einstein DVD. The Martin-Volpe apartment is a launch pad for a very civilized life: shopping, the odd museum outing, and dining at Chez Georges, near Place des Victoires. "It’s very old-school," Volpe says of the venerable bistro. "It really feels like the France of your dreams." Mostly, however, their days are spent hunkered down in libraries conducting research and haunting local auctions, separating the wheat from the chaff. "Trying to find the jewels in the sleeper sales—that’s the fun for us," Martin says. Several gems have made their way into the Paris apartment. New finds are likely to provide a dilemma, however, given how perfectly everything the partners own is arranged. "There’s limited space," Volpe admits. "The next time there’s something we can’t live without, we’re just going to have to make room for it."

The living room sofa is by Christian Liaigre, the armchair—designed by Grassi, Conti, and Furlani—is vintage, and the stainless-steel Rock tables are by Arik Levy; the Jansen stool and oblong David Hicks pillow are vintage, and the small pillows are made of a Clarence House silk velvet.

A Ross Bleckner etching, cowhide rugs, and curtains of Jim Thompson silk in the living room.

In an artful corner, Irving Penn’s 1976 Parisian Bog Mouse is displayed above a collection of bronze sculptures by Diego Giacometti.

In the entrance hall, a wall sculpture by Kim Chun-Hwan, a circa-1955 Gilbert Poillerat bronze-and-mahogany table, and a 1940s Italian side chair; the hanging light fixture is by Nathalie Pasqua, and the sconces are by Artemide.

A gelatin-silver photogram by Adam Fuss and 19th-century École des Beaux-Arts student drawings of floor patterns in the back hall.

A circa-1975 Joe Eula sketch of Babe Paley hangs above a headboard upholstered in vintage fabric printed with Picasso designs in Martin’s bedroom; the bed linens are by D. Porthault.

The powder room’s circa-1950 brass mirror is French, as is the vintage collapsible tripod table.

The Italian desk chair and Line Vautrin mirror are vintage, the mohair throw is by Hermès, and the bronze reading lamp is by Christian Liaigre.

The desk in Volpe’s bedroom has an Eiffel Tower view; the circa-1950 table lamp is by Georges Jouve, and the bronze disk is by Robert Courtright.