A furniture showroom may be the best place to buy a sofa bed, but perhaps it is not the ideal setting in which to sell serious antiques. At least that's the view of Mark Jacoby, who with his wife, Diana Jacoby, owns Philip Colleck, a 63-year-old gallery that specializes in fine 18th--century English furniture.

Mr. Jacoby recently moved his shop from a loftlike space downtown to a pre-Civil War town house at 311 East 58th Street. The house is possibly the only free-standing antiques store in Manhattan, and Mr. Jacoby has meticulously restored its three floors to show his merchandise in period rooms.

It is an expensive gamble, especially for a dealer in his 40's, when the number of New York dealers with shops is declining.

The handsome brick house, set back from the street, has an old-fashioned English cast-iron street lamp and a picket fence in front. There are trees on both sides, and a large garden in back. The house, designated a landmark in 1967, has classical proportions, and its red brick is set off by the white fence and black stone trim. If it did not have a sign, one would probably assume it was a single-family house.

"It's a simple Georgian, late Federal town house," Mr. Jacoby said. "Everything is symmetrical and straight. It could almost be an early-18th-century house."

The homey feeling is reinforced in the interior. The windows, moldings and wide-plank wood floors are original. A foyer with an elegant staircase leads into the main drawing room, which is carefully furnished with antiques, china and silver.

Ms. Jacoby, a board member of the National Antique and Art Dealers Association of America, decorated it in traditional wallpapers. Pictures and mirrors hang above the side tables. Chinese porcelain sits on the lowboys. It's welcoming yet private.

"It wasn't easy to find this place," Mr. Jacoby said. "We looked for two years before we purchased the building. But we had always wanted to display our merchandise in room settings, and we wanted to be back uptown on the East Side, where our clients are. We're also only a block from the D&D Building, so it's easy for designers and architects to visit."

The house has an unusual history. Up to now it has been a private house. Mr. Jacoby said it was built by a brick mason as his own house before the Civil War. In 1873 a Hudson Street printer occupied the house. In 1877 it was purchased by a Prussian-born merchant named Mathias Down.

In the 1930's Tennessee Williams lived there as a boarder, and in 1950 Mr. Down's grandson sold the house to Charles Jones, a San Francisco musician who moved to New York to teach musical composition at Julliard and the Mannes College of Music. Mr. Jones held master classes in the house and lived there with his family for nearly 50 years. He died in 1997.

Today one can buy a houseful of furniture there at one go. The floors display English furniture from the late 17th to early 19th centuries, along with mirrors, screens and accessories. There are sets of chairs, commodes, game tables, chests-on-chest, kneehole bureaus, leather screens - you name it.

"It's pretty much anything that would have been in an English country house in the 1700's," Mr. Jacoby said. In the 18th century, England was at the height of its commercial and military power.

"The burgeoning upper middle-class and aristocracy retired from dirty London into the English countryside to build grand houses," Mr. Jacoby continued. "They were formal showcases for their owners to display wealth, sophistication and taste. They often used the most fashionable architects and furniture makers of the day."

The styles represented included William and Mary, Queen Anne, George I, II, III, and Regency. "We look for pieces that are special, "Mr. Jacoby said. " Honest and beautiful in terms of design, color or surface decoration. We want pieces that bear proof of their age."

The current showstopper is a rare Queen Anne burl walnut bureau bookcase from about 1705, standing 8 foot 1. The piece is unusual because it was made in three sections. The top is like a cabinet, with adjustable shelves and eight drawers. Beneath its double-domed broken-arch pediment are a pair of doors covered with their original double-beveled smoky mirrors. Each is bordered in a beveled mirror frame.

"Glass was extremely expensive then because there was only a handful of glass houses in England that could produce panels this large," Mr. Jacoby said. "The glass would have been worth far more than the piece."

The center section has a slant-front desk with twin matched burl walnut veneers. It opens to reveal an arrangement of cubbyholes and drawers. The writing surface is waist high.

"This was a secretary made for a sea captain so he could write standing up, which is what captains always did on board ship," Mr. Jacoby said. "It's a nautical touch."

The desk, whose price approaches $500,000, has its original candle slides, hardware and keys. It even has old labels inside the drawers. One is marked "shaving things," another "waistcoats," another "old coats."

"A piece like this had multiple functions," he explained. "The man would have shaved in front of it."

Mr. Jacoby bought the desk at auction in London after researching its origin. It had been anonymously consigned by the owners of Walton Hall, the English manor house for which it was made 300 years ago. "Sometimes you get lucky," he said. "The family needed a new roof. To find a piece that has always been in the same family is extraordinarily rare."

Other exceptional pieces on display include a pair of beautifully painted Sheraton chairs with interlaced-heard backs, and early Queen Anne chair with cabriole legs, whose crest rail serves as a headrest on which a woman can lean her wig; a 17th-century lacquered Japanese cabinet with gilded copper mounts and a custom-made, elaborately carved gilt stand; a Chippendale mahogany concertina games table; and an eight-panel leather screen with Delftware plaques and painted Chinoiserie scenes.

Mr. Jacoby, currently chairman of the dealer's committee of the Winter Antiques Show, certainly knows his furniture. A Pittsburgh native and the son of an antiques collector, he studied art history at Kenyon College, spent his junior year in Rome and then took Christie's decorative arts course in London.

"You couldn't specialize in decorative arts in this country at that time," he recalled.

In 1980, fresh out of school, he went to work for Philip Colleck, a veteran English dealer who had set up shop in Manhattan in 1938. Renowned for his extensive knowledge of the field, Mr. Colleck trained Mr. Jacoby (and his wife, whom he met there). Mr. Colleck died in 1987 and left his entire estate to charity. The Jacobys bought the firm from the estate.

The Jacobys are part of a younger generation of serious dealers who are determined to succeed as shopkeepers. "I always recommend them," said Albert Sack, an Americana dealer in Manhattan who is in 80's. "I admire their efforts to be purists."