Tracy Campion of Campion and Company Real Estate has listed this elegant home, which has three bedrooms and three-and-a-half baths, at $2,800,000.

Overlooking Boston Common, a grand Beacon Hill townhouse at 35 Beacon St. between Joy and Walnut streets comprises five condominiums, and one of them, Unit 1, is on the market.

Tracy Campion of Campion and Company Real Estate has listed this elegant home, which has three bedrooms and three-and-a-half baths, at $2,800,000. It is unique, as it includes a private guest cottage behind the main building and a beautifully landscaped courtyard.

The entrance to the Greek Revival building is slightly below street level and bordered by gardens and a 19th century brownstone balustrade. French doors with sidelights open into a small vestibule and lobby with an elevator and staircase.

One flight up is the entry to Unit 1, which opens into a foyer that leads to the main living space. On the left are two closets and a powder room with a built-in for linens and a rectangular washbasin above a mahogany vanity. On the right is a stunning credenza that separates the foyer from the dining area. It has a two-sided china cabinet above a walnut buffet. Cupboards and drawers are underneath.

Straight ahead is the living room with two tall bow-front windows. The ceiling, edged with crown molding and centered with a medallion and chandelier, soars 12 feet. The flooring is dark-stained maple.

The dominant feature of this room is an original wood-burning fireplace with a mantelpiece of black marble with gold veins and a brick surround. The room is wide and flows into the dining area, which has another chandelier, a chair rail and both a pass-through and a pocket door to the kitchen.

A narrow wall of exposed brick hints at the home’s historic past, as the gourmet kitchen is quite contemporary. It includes mahogany counters, a stainless steel farmer’s sink and a Miele dishwasher. The four-burner Thermador gas range with a grill and a high-capacity oven stands under a ceramic backsplash of diamond-shaped tiles and a convenient pot filler.

Custom-designed cabinetry, including a pantry closet, and a stainless steel Sub-Zero refrigerator flank the range.

There is more entertainment space at the front of the home overlooking the Common. It is a light-filled library with floor-to-ceiling bookshelves and a wood ladder to reach the top shelves. Opposite are multi-paned French doors that open onto a Juliet balcony.

A second pocket door in the kitchen opens into the foyer and hallway to the bedrooms. En route are a side-by-side Asko washer and dryer behind pullout doors.

The second bedroom has been outfitted as a study. Its window looks out to the courtyard, and the compact en suite bath with a shower features sky-blue mosaic glass tiles.

The master bedroom boasts a floor-to-ceiling wardrobe that has closets above four rows of drawers, and at the top is a cabinet with recessed doors that hides a television. A second wood-burning fireplace here has a wooden mantelpiece with carved swags and thin Corinthian columns and a huge mirrored overmantel.

The marble-tiled en suite master bath includes a glass-enclosed deep soaking tub/shower with a sunflower showerhead and an undermount sink.

The French doors open to the brick courtyard and the guest cottage, which had been more like a shed before it was completely reoriented, rebuilt and refurbished about 10 years ago.

Beyond the multi-paned door with sidelights and arched transom is a large open sitting area plus room for a queen-sized bed. Custom-designed oak cabinets accompany the kitchenette, which has a built-in refrigerator and stainless steel sink and a long black marble counter. Three skylights brighten this space.

The full bath also has a skylight above the vessel sink. Outside is a terraced garden filled with flowering plants and a brick walkway that leads to an alley to Joy Street.

The townhouse was built between 1833 and 1834 for Samuel Turrell Armstrong, who had been a printer and bookseller before entering politics. He served as a state legislator at two different times as well as lieutenant governor and governor. When he became mayor in 1836, he oversaw the installation of the iron fencing surrounding the Common. He served in the state senate in 1839.

The brick and brownstone building remained a single-family house until 1930 when the entrance was altered and the building was turned into apartments. According to the owner, it was the first building in Boston to be converted to condominiums. That was in 1973.

The building has a common roof deck with spectacular views. It is a nice spot for watching the Fourth of July fireworks display.