The homes share many outstanding features. Engineered solid white oak seven-inch plank flooring (with a 25-year natural finish and a cork under floor - for added insulation and foot comfort) is installed throughout along with Pella historical architect series (E-star rated) double hung windows.

Built in 1860, this grand dame on a tree-lined street just off Monument Square in Charlestown now houses two stunning, brand-new duplex residences, listed by Frank Celeste of Gibson Sotheby’s International Realty.

One is a 2,100-square-foot parlor duplex with three bedrooms, three full bathrooms and one half bathroom listed for $1,715,000. The other, a duplex penthouse with 2,155 square feet of living space, three bedrooms, two full bathrooms and one half bathroom is listed for $1,839,000.

The homes share many outstanding features. Engineered solid white oak seven-inch plank flooring (with a 25-year natural finish and a cork under floor - for added insulation and foot comfort) is installed throughout along with Pella historical architect series (E-star rated) double hung windows.

Smart home systems by Control 4 and Building 36 control all locks, heating, cooling and entryway video. Control 4/Triad Sound Systems are also installed, but additional features can be added.

The millwork, however, is exceptional. Custom crafted to reflect 19th century designs and showcase the 10-foot ceilings (in the main living areas), these “period” pieces look as if they have always been in the building. Large bay areas have three almost floor-to-ceiling windows highlighted by period-style detailed wainscoting and triple cornice molding including picture-rail trim. All doors are in a Stickley-like design.

Jenn-Air stainless steel appliances used in both kitchens include a six-burner gas range with a professional hood (with a warming light), French door refrigerator and dishwasher accented by a square farmer’s sink under a window. Grohe Essence faucets are beautiful accent pieces. The kitchens, however, have their own personality as each has a different layout.

Unit 1 (the parlor duplex) has a galley layout with a center island with a microwave drawer and a waterfall edge. This also seats two. The backsplash - in a mini herringbone pattern - accents Cirrus colored cabinets that stretch to the ceiling and Statuario Quartz countertops. Several glass-front lighted sections at the top create an attractive transom-like effect.

In Unit 2 (the penthouse duplex), the kitchen is U-shaped and cabinets (Seashell uppers both glass-front or closed) stretch to the ceiling. The lowers are gunmetal blue. Here, the subway tile backsplash has a textured finish and the attached peninsula has a convenient pull-up electrical outlet strip.

In the fully open-concept layouts, which are also the norm, the “living room” of each unit has a stunning gas fireplace with a circa 1850 intricately-carved Carrara marble mantel that is in such pristine condition, the edges of the various patterns are still sharp. Period arched and decorated metal inserts are additional visual treats.

Each residence has a full-size stackable Electrolux washer and dryer adjacent to a half bathroom.

Of the three bedrooms, two are en suite and spacious enough to be master suites. All double closets - several are extra-wide - are lighted and will be customized to owners’ specifications.

Like the kitchens, all bathrooms have the same materials and fixtures: custom white quartz sinks and tops in floating vanities, Toto dual flush Aquia II commodes and Symmons Duro trims and faucets. Frameless glass doors are standard.

Step-in showers in the master spa-like bathrooms have linear drains, decorative product niches plus a wall, rain and handheld shower system. Large LED framed mirrors are over the vanities so well designed that every drawer is usable. Italian porcelain and natural stone mosaics combined in unique decorative patterns enhance the individuality of each loo.

Despite those similarities, no two of these lavish bathrooms are alike. In the bathroom on the lower level of the parlor duplex, for example, extra-long subway tile is used in the shower surround. In one penthouse duplex bathroom, 18-inch-square floor tiles and rectangular tiles (12” x 24”) go to the ceiling in the shower surround. The half bathroom in this unit has a honeycomb tile floor.

Each home also has “extra” living spaces. In the parlor duplex, an office nook is adjacent to a large bedroom and a huge media room is on the lower level. In the penthouse, a “bump out” next to the living room proper is large enough to use as a formal dining room.

These homes have additional perks, including large outdoor spaces. In the parlor unit, full glass pane French doors lead to the rear mahogany deck and down to an enclosed bluestone patio/courtyard with wrap-around seating. Along with piping for a natural gas grill, this private getaway has outdoor speakers.

The penthouse has two outdoor havens. One is a large deck off the second floor landing that leads to a huge roof deck with outdoor speakers and fantastic 360-degree views that includes the harbor and the Boston skyline. Keep in mind that this is one of highest spots in town.

Street level views are impressive, too. As all utility poles and wires are behind the houses, Chestnut Street looks much as did back in the day complete with “gas” lamps.