A late summer day in Florence, Italy, and the Piazza del Duomo is heaving. Tourists in shorts and T-shirts swig mineral water and squint up at the green-and-rose facade. Contessa Simonetta Brandolini d’Adda walks briskly through the throngs in a navy suit and matching slingbacks. Because of a phone call she made a few minutes before, the door at the Accademia Gallery will open—despite the fact that the museum is officially closed for the day—allowing the Contessa and her guests a private view of Michelangelo’s David.

A phone call from the Contessa is a powerful thing: It can get you a dinner with an Italian industrialist or a personal tour of the Vatican. But perhaps most important, it can help you obtain a slice of coveted real estate, like a Medici palazzo for a season. The Best in Italy, the real estate company Brandolini runs in Florence with her husband, Conte Girolamo Brandolini d’Adda, caters to the very discriminating—or at least the very rich—and frequently to the very famous, mainly from Great Britain and the United States.

The Brandolinis’ approach bucks the current internationalization of the real estate market. High-end real estate firms such as Sotheby’s International Realty, Savills, and Knight Frank—which opened a Florence office this past spring—increasingly cater to wealthy people around the world. “If you take your high-net-worth individuals, they don’t necessarily want to be in one country,” notes Knight Frank’s Bill Thomson. “What they really want is a lifestyle, and whether it’s in the South of France or Portofino or Venice, it doesn’t matter a whole lot.” Large, prestigious international firms are buying up smaller boutiques—or building partnernships with them—and are increasingly attracting listings from local sellers, who figure the international groups have a broader and more affluent clientele.

But the Brandolinis prefer to stay small and local. They offer not just houses, but entrees. “If someone needs, say, a palace in Milan or Palermo, you probably know who has one,” says the Contessa, describing her business. “Or if not, you know someone who knows someone.”

Like the European aristocrats in Henry James novels, Brandolini trades in connections, linking New World money with Old World nobility and property. Financier Felix Rohatyn, film mogul Paula Wagner, and ad supremo Charles Saatchi have all been clients of Brandolini’s. When Tom Cruise and Nicole Kidman were still married and sought a secluded Tuscan bolt-hole, the Contessa secured them the Villa Pisana, a stately 19th-century mansion discreetly tucked into a 7,400-acre estate outside Pisa. Sting, a longtime client of Brandolini’s, once brought along his mobile studio to record an album in his rental villa. Brandolini persuaded the owners—who weren’t quite sure what this blonde inglese actually did—not to balk at the trucks and hordes of technicians.

The Contessa’s clients are insulated from America’s current mortgage woes. So are the properties she specializes in: sumptuous mansions in regions like Tuscany and the Amalfi Coast. Though Italy’s housing market was relatively flat in 2006, prices for homes in prestigious locations bucked the trend, growing at about 10 percent, according to the 2007 Savills European Housing Review. “The market’s top end is much steadier,” says Charles Weston-Baker, head of Savills’ international division. “It’s the middle market where it’s fickle.” In Tuscany, for example, the market in crumbling farmhouses has slowed of late, but top palazzos have been moving nicely. Indeed, for wealthy buyers of second homes in Europe, many of whom are in banking, a rise in interest rates can be a boon: “If interest rates go up, these people are making more money,” observes Weston-Baker.

Brandolini’s listings are exclusive. Homes start at $3 million, and rentals range from $12,000 to $70,000 a week. Her current roster of about 80 properties includes a Sicilian city-palace; a Palladian villa; and the Villa Il Palagio, a 12th-century farmhouse turned into a glorious rambling estate, complete with faded medieval frescoes, Napoleonic camp beds, and a superb collection of still lifes. On an early fall day, the pool glints invitingly, the sun slants through the olive groves, and turtles creep along in the turtle garden. One of Il Palagio’s previous tenants was American philanthropist Shelby White.

In Italy, grand properties like Il Palagio rarely reach the sales market, Weston-Baker says, unless the aristocratic owners are faced with one of the “three D’s: divorce, death, or debt.” When they are, sales are often private. Savvy villa seekers have to hover, contacting a local lawyer or estate agent years in advance to express their interest in this villa or that palazzo should it ever come up for sale. In such cases, Brandolini’s impeccable connections prove priceless—and she’s not even a local. Born in the U.S., in Georgia, she was studying art history in Florence in the mid-1970s when she met the count, a widower with a three-year-old daughter. Their wedding made her the first American to marry into the Brandolini family. She brought American friendliness and an entrepreneurial spirit to the cozy—at times stuffy—Italian nobility. “My husband says, ‘You give the tu’ ”—the familiar form of address—“ ‘too easily,’ ” she laughs. “ ‘People will get too familiar with you!’ ”

The business began 25 years ago, when the Brandolinis rented out one of their three villas and realized how strong demand was. When the Contessa began trying to persuade Italian friends to let out their second (or third or fourth) homes, many initially balked. Rent the ancestral palazzo? It might look as though one didn’t have the money to keep it up oneself! But the pair had already set a radical example, and many others eventually gave in.

The Brandolinis decline to provide revenue numbers but have four full-time employees (more during high seasons to tend to guests) and rent about 100 properties a year. Their fee is included in the rental price. They have been approached by large real estate firms and have toyed with the idea of expanding beyond Italy. But their hands-on approach—the Contessa tries to meet each client personally and sometimes has them to dinner—means the Best in Italy needs to remain small and independent. Brandolini tells property owners to leave the family pictures and silver service in view. “It shouldn’t feel like a rental home,” she says. “It should feel like you’re a guest in the home—just without the owners there.”

For her 20th anniversary at Bank of America, Ann O’Brien, managing director of its private equity division, decided to take a summer sabbatical in Tuscany. She planned to have nearly a hundred houseguests, so she viewed around 25 properties before settling on two of Brandolini’s: a Palladian villa for two months and a rustic castle for a third. At both, the staff was outstanding, O’Brien says: Male houseguests got used to having their boxer shorts ironed, causing consternation among their wives. Brandolini’s unique selling points, says O’Brien, who previously had a disappointing experience in Tuscany with another agent, are “the diversity of properties, her attention to client detail, and the things other than just a property rental that she can bring to the table.”

Brandolini has found yoga tutors, vintners, obstetricians, and antiques sellers for her clients. One client wanted to learn more about art, so the Contessa arranged for art historians to tutor him; he’s now a world authority on Old Masters. A Manhattan opera aficionado requested singers for nightly recitals in his villa; later he flew them out to New York to sing for him there too.

Occasionally, clients’ exacting standards can border on the obnoxious. One famous client required that all her furniture be white. The Contessa duly had the villa’s contents covered, only to have the client carp that the sheets weren’t monogrammed with her initials. She also informed Brandolini that she did not speak directly to servants and wanted Brandolini to do it for her. Brandolini replied that it wasn’t the done thing in Italy. “I feel,” she laughs, “as though I’m somewhere in the middle of the Atlantic.”