This unlikely space is the work of architect François Roche, built in 2003 for a French couple as a hideaway where they could admire their contemporary art collection. The house, which recently went on sale for €1.58 million, belongs to the category of what the French call maisons d’architectes—20th- and 21st-century homes designed by recognizable names or of architectural interest. While this has already become a coveted sector in the U.S. real estate market (where the recent auctions of the Kaufmann and Esherick houses created serious buzz), it is just beginning to develop a following in France.

France’s architectural heritage from 1920 onward is particularly rich, including internationally renowned signatures such as Le Corbusier, Robert Mallet-Stevens, Jean Prouvé, and Rudy Ricciotti. Many have designed homes in and around Paris, but until recently there was no way of knowing what was on the market without contacting every agency in town.

A year ago, the Paris-based realtor Nicolas Libert partnered with an architectural historian to open the agency Architecture de Collection (www.architecturedecollection.fr), wholly devoted to this specialized sector. The pair describe themselves as architecture "dealers," treating homes like works of art, and offering an in-depth documentary background for every property they handle, including the Roche house. "When a buyer chooses a house like this, it’s a gut reaction, an instinctive purchase," says Libert. "You open the door and your jaw drops."

For Philippe Starck acolytes, Architecture de Collection recently listed a house conceived by the superstar designer in 1987, on an island just outside Paris, for €2.73 million. Nicknamed the two-faced Sphinx for its monumental front and back staircases, the interior is vintage Starck—from the concrete inner walls to the sculpted metal light switches—while the backyard slopes down to the Seine with a boat slip at the end. (Right next door, a larger Starck house was listed for €10 million by the agency Belles Demeures de France, a Daniel Féau affiliate.)

Paris has one other agency specializing in modernist and contemporary homes, run by Muriel Auclert (www.maimmobilier.fr). She says her goal is "to promote this patrimony for its historical value." Her recent listings include a €3.8 million five-story cubist house by Mallet-Stevens, on the street named for the architect. Auclert also listed a penthouse with a vast roof garden in Le Corbusier’s famous Villa Stein, 10 miles west of the city, for just under €1 million. She calls the latter a "masterpiece of modernism" by one of the most celebrated names in architectural history.

The typical clients for these unconventional properties are generally French, aged 30 to 50, often working in the arts, and—unsurprisingly—passionate about architecture. "These days, the collectors of architects’ homes are excited about the idea of having two, three, even four houses," claims Libert, adding that the boom in contemporary art has contributed to this trend.

Auclert says it’s still a niche market in France, with higher values than traditional properties, yet difficult to price because each one is so unique. (It’s worth noting that the general real estate market in Paris remains a relative bargain when compared to cities such as London or New York.) And location is crucial. Western Paris, including the city’s ritziest suburbs, is a particularly fertile area for 20th-century homes. But nothing beats an address right in the city—the more central the better.

The highest end of Paris’ property market is the domain of sellers such as Daniel Féau (www.feau-immobilier.fr) and Sotheby’s International Realty (www.proprietesparisiennes.fr). They each number several exceptional architect-built homes among their offerings, with steep prices aimed primarily at foreign buyers. In the 16th arrondissement, for example, Sotheby’s recently listed a contemporary townhouse built in 1999 by the young Italian architect Stefania Stera for a wealthy couple. Resembling an ocean liner, it measures nearly 12,000 square feet with seven terraces on five levels, a pool, custom-made art and furniture, as well as a garden filled with azalea bushes. Its eye-popping price tag: 30 million.

"Before the dollar effect, these were the types of properties Americans would buy," says Pascale Catteau, associate director of Sotheby’s International Realty. Four years ago, Americans made up 50 percent of her clientele, but now they are increasingly scarce. Nonetheless, it was an American, former commodities trader Robert Rubin, who managed to acquire Pierre Chareau’s iconic Maison de Verre for an undisclosed sum in 2006.

Sometimes a house’s story nudges the price up even more than its design. The greatest selling point of architect Emilio Terry’s 1930 mansion in the suburb of Boulogne is that it was inhabited by Édith Piaf and her lover, the boxer Marcel Cerdan. (It seems the singer planned to turn the living room into a ring.) When the current owner bought it 12 years ago, the home was occupied by squatters, but last spring it was listed by Sotheby’s International Realty for €8.2 million—and advertised only outside of France. Architecture is one thing, but association with high celebrity and an Oscar-winning film are assets few homes can claim.

Buying Property in France

• A good international lawyer is invaluable in negotiating the ins and outs of the French banking, legal, and tax systems

• Normally it takes three months from the preliminary contract to the deed of sale. A buyer (but not the seller) has seven days to reconsider an offer after signing the preliminary contract. After that, the security deposit is forfeited

• Additional fees include notary fees, registration, real estate agency fees, and annual taxes

• When buying an important historic home, keep in mind that maintenance will probably be more expensive than for a standard property, due to the building’s uniqueness