Thanks to the extensive design background and aesthetic perception of the owner and her mother, the 2,107-square-foot, two-bedroom Unit 3 at 112 West Concord St. feels more like an autonomous townhouse than a condo penthouse.

It took a designer’s eye – two, to be exact – to transform the top two floors of a narrow 1899 South End rowhouse into a two-level, three-dimensional spectacle of light, space, finishes, details and the outdoors.

Thanks to the extensive design background and aesthetic perception of the owner and her mother, the 2,107-square-foot, two-bedroom Unit 3 at 112 West Concord St. feels more like an autonomous townhouse than a condo penthouse.

Fine woods, stones, tiles and wall treatments permeate the spaces. Multiple skylights shed light on all cooking, dining and entertaining, and even some bathing. The private rooftop terrace is made to order for al fresco dining amid far-reaching Boston skylines. The front and rear bay windows expand and brighten all common and bedroom spaces so you always feel like you’re at the front of the house no matter which end you occupy.

To boot, more than half of the building’s central turned-baluster staircase is all yours, allowing you a private walkup into the open, airy hall that introduces the bedroom level. From here, a skylight lightens your ascent all the way to the roof.

This direct entry also means convenience, letting you retire for the night upon returning home.

The laundry room is at hand as well, enriching your washing and sorting chores with a backsplash of pattern-stacked rough marble mini-bricks going up to the ceiling.

Equally convenient is the immediate presence of the master bath at left and the walk-in closet at right upon entering the master suite. The bath boasts a marble-like tile floor, walls of tiles with a wavy sand-dune aesthetic, an octagonal corner glass standup shower with wall-niches for hair and body products, and a farmer’s sink on a black laminate vanity that projects out of the wall, yielding more room for foot-level storage. The walk-in closet has a full array of built-ins for all kinds of clothing.

The master bedroom abounds with space and light. The wide bay of double windows offers intense southwestern exposure. An ample wall area is available for a king-size bed plus sizable nightstands.

The ceiling is lowered at the bay window, setting it off as an intimate sitting area.

The second bedroom across the hall grows with the child, remaining suitable from nursery to teen-room phase - courtesy of its baby-blue walls, a generously carpeted play space and a wall of folding-door closets accommodating a growing wardrobe. Further growing the space is a bay-window sitting area with rise-and-shine northeastern exposure onto the street.

The private en suite bath is complete with a deep soaking tub with hand-held and fixed shower heads, a vanity with towel rack and shelf and wood grain ceramic tile floor, There is also a contrast of marble treatments - smooth tan for the tub, rugged stacked mini-bricks for the vanity wall.

The entertaining arena sweeps across the top floor in the form of a bright, open kitchen-living-dining area that passes through the sunny central landing into a front-view family room/library.

A skylight beams directly on the kitchen sink on the soapstone island counter to illuminate after-dinner cleanup, also facilitated by the dishwasher and trash compactor built into the island.

The kitchen’s L-shaped soapstone wall counter incorporates a six-burner gas range, a stainless steel backsplash embossed to suggest bricks, paneled cherry cabinetry with stainless steel hardware and a wine cooler. A deluxe stainless refrigerator is beside the counter.

For convenient food and cleanup service, the island faces the dining area, which has an industrial-style chandelier of filament light bulbs projecting from a structure of black rods. The living area’s cynosure is a broad, deep bay window topped by a finished octagonal pine-plank turret dome climaxing in an octagonal mini-skylight.

The full bath off the landing features a step-up soaking tub with stationary and retractable hand-held shower heads, where a skylight turns your bath into a sunbath. White tiles and Carrara marble borders, risers and sink counter intensify the light. A mosaic-tile floor and stringcourse add tasteful accents.

The family room/library receives ample entertainment-center space from the mansard roof’s broad bay-window dormer. A two-wall complex of built-in shelves, running counter and desk space provides full office/study accommodations. A grasscloth wall treatment lends a classic look and a stainless steel ceiling fan relieves summer heat.

Light from the hall and living area enters through a transom over the pocket door, which can be closed for private study.

The private full-roof terrace treats your guests to stunning city views from many directions: Roxbury’s landmark standpipe on Fort Hill to the southwest, the John Hancock and Financial District towers to the northeast, and a contrast of Back Bay skyscraper and low-scale South End rowhouse views to the sides. Green plants and evergreen trees soften the urban hard edge with garden intimacy.

For a more public garden setting, Newland Street Park across the street offers a quiet, tree-shaded sitting area along a winding brick walkway (displaying Miriam Knapp’s abstract metal sculpture “Cityscape III”), as well as a children’s climbing and sliding complex on the adjacent playground.

Offered at $2,675,000, Unit 3 at 112 W. Concord St. turns urban penthouse living into the ultimate architectural experience, seamlessly blending classic with contemporary.

For a private showing, contact Valerie Post or Keith Shirley of Engel & Völkers Boston at 617-908-4000 or postshirleyteam@gmail.com.