Upon entering the unit, step into convenience as well as class.

What does the word “penthouse” conjure up? Sky views from glass walls and sweeping decks? Sun-splashed, clean-lined, open-concept spaces? Sitting on top of the world? Or the old-fangled image of a weather-beaten toolshed tacked to the back of a house?

Unit 7 at 184 Marlborough St. in the Back Bay thankfully bears no hints of the latter, but nor does it quite follow the format of the former.

This 1,912-square-foot, three-bedroom duplex was refurbished and embellished in 1990 with lavish traditional details – paneled wainscoting, crown moldings, baseboards, turned balusters, marble baths, granite counters and floors, classic fireplace, ornate brass sconces, patterned carpeting and wallcovering – in league with the French Academic architecture of the original rowhouse designed in 1881 by Clark & Curtis.

The result is a penthouse that doesn’t feel like one. It feels more like a tastefully classic home, grounded enough in its historic neighborhood to mitigate any fear of heights, top-of-the-hub hubris or remote isolation from civilization, even amid the urban garden aura of the front balcony and three-tier roofdeck.

Yet, modern penthouse conveniences are still there in the form of skylights, sunny city views, automatic plant irrigation and deck lighting. There’s also the Otis elevator service from the elegant lobby, where moldings, paneled wainscoting, patterned carpeting, brass sconces and framed renderings of Palladian classical buildings preview the grandeur to come.

Upon entering the unit, step into convenience as well as class. A coat closet with hidden back-door storage space is at left next to a stacked washer/dryer closet and the marble master bath is on the right.

The luxurious master bedroom and office-suitable second bedroom are straight ahead - for those who want to get right down to business, jump into bed or shower and shunt off.

But be sure to stop and enjoy the elegance of the bath’s green granite double-sink vanity with mahogany cabinet and scroll-handled faucets, Carrara marble-tiled floor and tub/shower with a seven-spout showerhead, ornamental brass dual-lamp sconces, and black-and-white-striped wallcovering with classically scrolled and festooned frieze.

The master bedroom is calmly carpeted in blue-gray, wall-treated in muted aqua and appointed with window valances that complement the crown molding and baseboard. A handy hall of folding-door closets, including a walk-in, connects to the bath.

A double French door introduces the adjacent bedroom/office, where blue walls create serenity for study or sleep.

For those eager to eat and drink, the stairs to the living-dining top level is even closer to the unit entry. The stairs lands at a skylit hall with more of a penthouse feel, being immediately open to the skylit dining room and kitchen at left and the lofty living room and wet bar up a short flight to the right, bringing end-to-end space and light.

The formal dining room is dressed for dinner with an egg-and-dart crown molding, paneled wainscoting, light blue walls and lavish brass dual-lamp sconces.

The kitchen floor is mainly made of an unusually large piece of granite matching the facing counters and backsplashes. The granite’s erratic variegation is nicely balanced with cream-colored classic cabinetry, beige-and-white-striped wallpaper and a full range of stainless steel appliances, including a five-burner gas cooktop and a Sub-Zero refrigerator. A square pot-and-pan rack handily dangles from the skylight.

Off the dining room is the carpeted third bedroom. Its en suite bath boasts a marble floor and tub/shower, a granite vanity and a picture-framed mirror set in a mirror-wall, lending portrait dignity to your just-woke-up face every morning.

The hall, lit at night by a merry-go-round chandelier of lampshaded candleflame lights, also accesses a pocket-doored powder room with a marble floor laid on the diagonal, an egg-and-dart crown molding and a carved wood Chippendale-style vanity reconstituted with a marble-brick counter.

The elevated formal living room begins with a cocktail-ready wet bar with granite counter, mirror-backed glass shelves, mirror-wall and utility closet. The living room’s tray ceiling, crown molding, green marble fireplace with classic mantel and gray/brown wall treatment set the scene for elegant entertaining.

Two double French doors extend the entertainment out to the front balcony, which offers not only stunning city/street views and front-row seats for the Fourth of July fireworks, but also lighting from classic lantern sconces, automatic timer-set irrigation of plants, and a Roman arched and columned fountain with ram’s-head spout.

The private roof deck gives al fresco dinner parties a European feel. Three levels of decking planted with flowers, trees and shrubs make each seating area an intimate setting for the picturesque neighborhood views with space for awe at the distant sights of the gilded State House dome and the blue-glass Hancock Tower. Even if rain forces the party inside, sunlight still abounds, courtesy of the historic Back Bay’s low rooflines.

Offered at $3.4 million, Unit 7 at 184 Marlborough St. puts you in the upper echelons of urban living while keeping you grounded in historical tradition, for a unique penthouse-townhouse experience.

For a private showing, contact Cheryl Marsh of Marsh Properties at 617-797-5781 or Cheryl@BostonLuxuryRealEstate.com.