The rooms are large, bright and airy throughout. While the gleaming hardwood floors are striking, the variety of ceiling heights, configurations and contours is intriguing. The floor-to-ceiling windows add natural light and interesting views.

Once upon a time in 1859, Boston College shared its T-shaped quarters with Boston College High School (aka BC High – chartered and reopened in 1863) on a large plot of land next to The Immaculate Conception Church between Harrison Avenue and Father Francis Gilday Street in the South End.

While the college relocated to Chestnut Hill at the turn of the century, the high school stayed on the site until it outgrew the space in the late 1940s, moving to Columbia Point.

In 2008, the building was repurposed into 59 condominiums – known as The Penmark Residences – featuring dozens of unique floor plans and sizes seamlessly blending the old with the new, now unrecognizable from its former classroom days. One of those rarely available and sought-after deluxe units is now for sale, where you can live happily ever after.

Unit 101 at 21 Father Francis Gilday St., listed for $1.295 million with Jay Plasteras of Gibson Sotheby’s International Realty, is a 1,350-square-foot contemporary duplex home that is both welcoming and regal with the charm and sophistication one would expect of a residence located in a prime area.

Although the stately brick building still proudly adorns its signature arched windows of the former BC’s auditorium and its graceful arched entries, “There’s nothing old about (the unit itself) other than the gorgeousness of the space,” said agent Sean Spaulding. “You get the best of both worlds.”

The rooms are large, bright and airy throughout. While the gleaming hardwood floors are striking, the variety of ceiling heights, configurations and contours is intriguing. The floor-to-ceiling windows add natural light and interesting views.

The first floor features an expansive open-flow floor plan. The kitchen-living-dining room combination creates a perfect space for entertaining.

The double four-over-four large paned windows in the living-dining area not only provide natural light, but also welcome the residents and guests alike with an immediate view of the outdoor courtyard. This is an oasis in the heart of the South End. The window shelf is a perfect spot to add more greenery or pieces of art to enhance the contemporary feel of the space.

The U-shaped kitchen is tucked into a corner with plenty of custom cabinets and granite countertops along with top of the line stainless appliances – Bosch cooktop, convection oven, dishwasher and a Jenn Air refrigerator. It is a distinct space of its own. The breakfast bar peninsular has seating for three.

A conveniently placed powder room has a lovely pedestal sink.

A staircase – carpeted with 100 percent New Zealand wool, another reflection of the high quality finishes found in the home – leads to a hardwood foyer on the lower level. A stackable full size Bosch washer and dryer is discreetly hidden behind a door in the hallway. The flexible space of an interior room with a large closet can be used as a second bedroom, an office or den.

The master suite is lovely and spacious. The en suite bathroom is both large and beautiful. Linear mosaics provide the backdrop for the vanity. The tiled walk-in shower has a glass-enclosure. The bedroom features a large customized walk-in closet, complete with shelves, baskets and hanging spaces. Double sliding glass doors open to a private patio and an interior courtyard beyond.

No matter which outdoor space you choose, “you’re surrounded by trees and nature,” Spaulding said. “It’s secluded.” While the patio, one of just three in the building, is truly an oasis of outdoor space to relax, barbecue and entertain guests, the beautifully landscaped courtyard is a perfect place to read a book.

Even the street itself is lovely and peaceful. Long gone are the days when the old South End Burying Ground across the street was used as an active cemetery (1810-1866); although there are only 20 grave markers, more than 11,000 people are buried there. Since building on the land has been prohibited, the site will forever remain the beautiful touch of green – with historical significance – that it currently is.

The building itself has strong bones with a lot of architectural interest.

“They don’t make buildings like this anymore,” Spaulding said. “This type of construction is solid.” The building is also well-cared for, “it’s immaculate inside and out.”

The outside has been repointed and the systems inside have been updated. There are plans to redo the inside hallways and common areas with a fresh coat of paint, carpeting and lighting, as well. All owners have had an increased assessment for those upgrades; since the current owner has already paid the fee for the year, the new owner of Unit 101 will reap the benefits.

The pet-friendly building features a part-time maintenance superintendent on Mondays, Wednesdays and Fridays. Concierge services for package and laundry pick-up/drop-off are provided 24/7 in the St. James Court property just a few steps away either through the courtyard or the front entrance on West Newton Street

Direct access secured underground garage parking for one car is included as is a locked storage bin and a bike rack in the garage. There is also a large exercise room.

For professionals, young couples, empty nesters or most anyone who wants the convenience of city living with the quiet of the suburbs, 21 Father Francis Gilday St. is the location to be.

“You’ve got this incredible lofted great room for entertaining, relaxing or cooking; then you do down to your private quarters and your exclusive back patio. It’s protected from the elements of the city but still in the city.” Spaulding said.

The building is within walking distance to a number of schools, churches, galleries, boutiques and parks peppered around the neighborhood. Known for its international cuisine, most any type of ethnic eatery can be easily reached including Toro, one of the hottest tapas restaurants; The Elephant Walk featuring Cambodian and French cuisine; an Eastern Mediterranean -Armenian Lebanese “fine-casual” dining experience at anoush’ella which means “May It Be Sweet;” and a Mexican eatery, El Centro.

For great food with heady aromas, not to mention cooking classes, visit the Flour Bakery and Café, a favorite for all the locals. Since there are lots of bike lanes and the terrain is “flat as a pancake,” bicycling is also common and convenient.

There will be an open house from noon to 2 p.m. on Sunday, Oct. 7. For more information or for a personal viewing of the property, contact Jay Plasteras of Gibson Sotheby’s at 617-680-6060 or J.Plasteras@SothebysRealty.com.