After two years under Oxford Properties Group’s ownership, 125 Summer St. in Boston is nearing full occupancy following completion of a new lobby and main entrance.

For a component of one of the biggest-ticket commercial transactions in Boston history, 125 Summer St. managed to fly below the radar in most discussions of the city’s premier office buildings.

Just over two years ago, the 22-story tower’s occupancy rate was 65 percent. The 475,303-square-foot building across from South Station was marketed as the “value-add” opportunity in a five-building portfolio being sold by Blackstone Group, and Phil Dorman knew some of the reasons why.

“I would describe that as a euphemism for ‘the building that nobody wanted to buy on its own and got packaged with a bunch of buildings that people wanted to buy,’” said Dorman, director of leasing for Oxford Properties Group’s Boston office. “It really had never performed in its life cycle. It was beaten down in the marketplace and nobody wanted to move there. But we loved the building and the location and the opportunity to turn it around.”

Today the tower is 95 percent leased and an office tenant has signed a letter of intent for the largest remaining availability, nearly 24,000 square feet on the second floor, Dorman said.

Oxford paid $2.1 billion for the Blackstone portfolio, including $242.5 million for 125 Summer St. But it was the last $10 million of capital improvements that have made all the difference.

Separating From The Streetscape

Completed in 1987, the building’s design reflected the architectural trends and downtown landscape of the era. The main entrance and lobby were located on a shady block of Summer Street, wedged between a row of older buildings. The original postmodern architecture, designed to mesh with the surrounding low-rise buildings, didn’t help, said Larry Grossman, a senior principal with architects Stantec.

“At the time there was a huge desire for contextualism, meaning keeping the existing fabric of the city and trying to blend into it,” Grossman said. “It was contemporary construction, but made to look more historical. What we realized was that it was a building that was hiding, but in plain sight.”

Visitors who did manage to find their way to the building found a lobby sparsely populated by retail amenities such as a falafel shop. Stantec’s recommendation for the renovations, which began last spring: start over, beginning at the bottom.

The big opportunity, Grossman said, began with a rear entrance overlooking a small plaza created after the Big Dig. It faces the Rose Fitzgerald Kennedy Greenway, where the after-work crowd now gathers for lawn games and concerts in the summer.

“The critical density has changed from the 1980s, and South Boston and the Innovation District are huge draws,” Grossman said. “There’s been a density shift from the core Financial District, and South Station is the hinge in the middle.”

The new entrance leads to a security-equipped lobby with swanky couches and a modern, brightly lit seating area for visitors and building employees looking for a change of workplace scenery. The overall effect is closer to living room than lobby, Grossman said, reflecting the casual workplace trends popular among creative economy tenants. Gone is the falafel shop, replaced with warm interior finishes that would look at home in a hotel and lounge areas for casual meetings.

Moving the front entrance gave the building more visibility, particularly for South Station commuters, and raised the building’s profile among potential tenants.

With unseasonably warm weather hitting the city in February, Oxford is already looking ahead to maximizing the value of the 4,000-square-foot plaza in front of 125 Summer’s new entrance. Plans include outdoor tables, Adirondack seating and solar charging stations. It’s also looking for new retail tenants to generate more street-level activity and replace the former entrances on Summer and Lincoln streets.

Since making a splash with its $2.1 billion acquisition in 2014, Oxford Properties Group has become the second-largest commercial landlord in Greater Boston with a 4.5-million-square-foot portfolio. The Toronto-based company manages the real estate investments of the $77 billion Ontario Municipal Employees Retirement System. This month it added another high-end office building with the $202.5 million acquisition of 25 First St. in Cambridge, in a joint venture with Israeli real estate company AlonyHetz. Online marketing company HubSpot is the anchor tenant and has expansion plans to occupy the entire building.