It had already been a very good day, proprietor Michael Goldstein said at midmorning last Friday as he ushered me back toward his cubbyhole office behind the sales floor of Park Avenue Liquor Shop. Mr. Goldstein, a big man in his early 60s, had just sold three bottles of wine.

That might not seem like the sort of sales volume that would pay the Midtown rent. Mr. Goldstein’s isn’t running your typical neighborhood bottle shop, however, and these weren’t your average three bottles. They were imperiales (holding eight normal-size bottles) of ultra-desirable Chateau Petrus in vintages 1961, 1982, and 1990. Shielding the name of the customer, Mr. Goldstein checked the total on his computer: $188,770.

Nothing about Park Avenue Liquor Shop, shaded by a plain blue awning on Madison Avenue (not Park, as one might expect) at 41st Street, its windows displaying booze with nary a bottle of wine in sight, hints that this is a premier source for the world’s rarest and priciest wines. Walk in, and you’re flanked by cartons of standard stuff, including Woodbridge Merlot, Beringer White Zinfandel, and a closeout on Dry Creek Chardonnay, all priced under $8. Check out the cooler to the left of the entrance, however, and you’ll notice eye-popping rarities: Chateau d’Yquem 1942 and Chateau Petrus 1970, and Cros Parantoux 1978 from Vosne-Romanee, highly prized because it was made by Henri Jayer, now retired, who crafted red Burgundy the way Stradivarius fashioned violins. For the price of any one of these bottles, one could load up on dozens of cases of the budget busters.

Some wine shops segregate their priciest wines in dedicated “treasure rooms.” Here, the least and loftiest bottles mingle on the crowded shelves, as do customers on the sales floor picking up a $5 bottle and those scouting for a $500 wine.

With nothing locked down, accidents are inevitable, sometimes on a titanic scale. Once, for example, a jeroboam (holding six normal bottles) of Chateau Mouton Rothschild 1937 was on display at the center of the shop; it had been autographed by Baron Philippe, the owner of the property, which increased the value of a bottle that would already be worth between $50,000 and $60,000 today. “Signed, it would be priceless,” Mr. Goldstein said. One day, a shop employee backed into the giant bottle, and suddenly the floor ran purple with the lifeblood of Bordeaux. The distressed employee ran out the door and disappeared. Mr. Goldstein, a silver-bearded man with an easygoing manner, took the loss in stride, even though the bottle was uninsured.

The shop itself, a mere 2,600 square feet, is crammed literally to the rafters with wines. Uppermost, reachable only by ladder, are bottles of port, Madeira, and Armagnac, some dating back to the 19th century. Most of these, known as “birthday bottles,” are purchased to mark a birth year. “For next year,” assistant manager Peter Caturani told me, “we’ll order vintages ending in ‘6.’” Currently, 5,800 different items are stocked, according to Mr. Goldstein, including 526 from Bordeaux, 366 from Italy, and 1,048 from California. The shop also has an unsurpassed selection of single malt Scotch whiskies, overseen by Jonathan Goldstein, Mr. Goldstein’s son, including exclusive bottlings, which he has first tasted and then purchased in cask. Only a fraction of the shop’s inventory of 14,000 cases can be displayed on the sales floor or accommodated in the far-larger, catacomb-like warren of wine-storage rooms beneath it. The overflow is stored in four additional temperature-controlled wine vaults in New York and New Jersey.

Why is Park Avenue Liquor Shop on Madison Avenue? “The original location was on Park Avenue between 40th and 41st streets when my father bought it in the mid-1950s,” Mr. Goldstein said. In 1976, the shop moved to East 40th Street, and later moved to its current location. “We kept the name because of the mystique,” said Mr. Goldstein, who had a career in banking before taking over the store following his father’s death in 1965. Explaining the career change, he said, “I liked people.” He learned about wine and how to sell it from Victor Puppin, the sommelier of Brussels, a legendary, long-gone society restaurant, who directed diners to the wine shop. “One of the regular customers appraised estates,” Mr. Goldstein said, “and one day he called me to ask if I would appraise a wine cellar. And that’s how I got started with rare wines.”

Mr. Goldstein trades by phone, fax, and Internet with the trophy-hunters of the wine world, few of whom have set foot in his shop. Still, he insists that “wine is not meant to be snobby” and welcomes walk-in traffic. As we spoke, two Internet orders appeared on Mr. Goldstein’s computer: one from Brazil for luxury-priced French and Portuguese wines, the other from Lowell, Mass., for two bottles of inexpensive liquor. Why would anyone order items from Manhattan that could surely be bought locally? “Convenience,” Mr. Goldstein said. “We’ll send it to the door.”

Not every order is sent directly to the door, however – at least not right away. That trio of imperiales of Chateau Petrus that Mr. Goldstein sold on Friday morning, for example, were actually resting in the cellar of another collector from whom he had bought wine. “This guy is on his yacht somewhere in European waters right now,” Mr. Goldstein said. “He’s the only one who has a key to his cellar, so I have to wait until he comes home before I can take possession of the wine for my customer.” It’s the kind of problem that most other wine-shop owners only dream about.

Recommended Wines At Park Avenue Liquor

CALVET-THUNEVIN “HUGO” 2002, COTES DU ROUSSILLON-VILLAGES ($55) “We all flipped over this,” Mr. Goldstein said. “It’s so concentrated that you can almost chew the fruit. Tannins are light and yet the taste is full.” A blend of Grenache, Syrah, and Carignan from Provence.

ROCKET SCIENCE 2002 ($40) One could jump to the conclusion that a wine with a rocket ship on the label is just a novelty. In fact, when I picked up this bottle, a chorus of praise came from the sales staff. A red-wine blend, it’s the second label of Caldwell Vineyard, a top rated boutique winery in Napa Valley.

LA ROSEE DE MONBOUSQUET 2004 ($14) “Lotta flavor, not sweet, good mouth feel, and it tastes like real wine,” said Peter Caturani, an 18-year veteran of Park Avenue’s sales floor. “It’ll go perfect with chicken grilled outdoors.”

BOURGOGNE, HAUTES-COTES DE NUITS, “CLOS SAINT-PHILIBERT,” DOMAINE MEO-CAMUZET 1996 ($24) From a small red-wine specialist who planted a patch of chardonnay on stony soil on a hillside above Vosne Romanee in the early 1990s. Bright, mineral-laden aromas and taste. Not big bodied, but “back-loaded” with intense flavor that doesn’t quit. At its peak now. Finding older, fully expressive white Burgundy at retail isn’t easy, but you’d never know that, poking around Park Avenue Liquor Shop.

Park Avenue Liquor Shop, 292 Madison Ave., 212-685-2442, www.parkavenueliquor.com. Free delivery in Manhattan below 110th Street on orders of more than $50.