Babbo, the celebrated Italian restaurant off Washington Square, has a big reputation and a bigger celebrity chef in Mario Batali. So why shouldn’t it have a sizable wine cellar to match?

Well, because Babbo is located in the old Coach House space on Waverly Place, a cubbyhole of an address that once had a basement so shallow you had to stoop over as you entered. But that all changed when the contractors excavating the cellar of the building next door offered to do the same for Babbo; the owners, Mr. Batali and Joe Bastianich, jumped at the chance.

“We went from ‘Being John Malkovich’ to ‘Alice in Wonderland,'” the restaurant’s wine director, Colum Sheehan, said recently, referring to an office in “Being John Malkovich” with a floor that was half the normal height. Work began in mid-2005 and concluded last summer. The floor was lowered a good 3 feet — you can still see where the original stonework ends — and workers broke through the back wall, digging through solid earth until the basement extended fully beneath the kitchen. The grand double doors lead to the cellar, where the room once ended.

To walk through those doors is to pass into a wine wonderland. Babbo surely has one of the roomiest wine cellars in New York, a room equal in size to the first-floor dining area. There is elbow room between the stacks and each square wine nook has plenty of space for more bottles. “I love to bring industry people down here and show them what we have,” Mr. Sheehan said with a gleam in his eye. “I can’t jump up and touch the ceiling. And there’s lots of room still.”

The wines enjoying all this breathing room are exclusively Italian, save for a few champagnes, sherries, and ports. They have a friend in Mr. Sheehan, a native of upstate New York who has been a fan of Italian wine since his days as a student in Italy during the mid-1980s. His pronunciation is conscientious to a fault; terms like “Valle D’Aosta” and “Passito di Pantelleria” pop out in high relief.

“If distributors don’t know we sell only Italian wine, and they bring out something else, we tell them to put it away,” he said. The list of roughly 1,000 labels has not changed much in spirit since Mr. Sheehan took over the wine directorship a little over a year ago from David Lynch, who was moved up to general manager of Babbo. (“If it ain’t broke, don’t fix it.”)

However, Mr. Sheehan did flip the list on its head. Sharp-eyed diners will notice that the lineup of whites travels from Friuli-Venezia Giulia in the north down to Sicilia and Sardegna. But the red selections begin in Sicilia and move up in latitude.

“It’s a little roundtrip of Italy,” he said. “On our wine list, it’s very difficult to fit everything on to a single page in a lot of situations. You don’t want it to be just a random representation of regions. You try your best to make it make sense. … Part of the logic of going from the south to the north with the reds is it puts Tuscany and Piedmont toward the back of the list, so people will page through the other interesting selections before they get to the same-old same-old.”

Among the whites, the best-represented region is Friuli, which, with its mineral-driven sauvignon blancs and Tocai Friulanos, has become Italy’s pre-eminent white wine region. This is not surprising: Mr. Bastianich has vineyards there. Several of his bottlings — including Vespa Bianco, a blend of several grapes — are featured at Babbo.

Another novelty on the list is its full page of Italian dessert wines. Most oenophiles are familiar with Piedmont’s Moscato d’Asti and Tuscany’s Vin Santo — though Mr. Sheehan cautions this is “the real McCoy,” not “the industrial-produced imitation Vin Santo that comes compliments of the house with a plate of cookies.” But beyond that, local treats from Calabria and Alto Adige, both white and red, are probably unknown to all but the most discerning Italophiles.

Mr. Sheehan likes it that way. “One of the advantages of selling only Italian wine is you have a lot more space to bring in the less-thought-about regions. I don’t have to waste my pages on wines from Napa.”