By Catherine Carlock Globe Staff,Updated June 14, 2023, 12:01 a.m.

A park in the sky. A pool deck at around 450 feet, facing the western sunset. Ritz-Carlton branded condominiums with floor-to-ceiling glass windows.

These are just some of the features expected at the 51-story tower under construction now above South Station — a project that’s been in the works in some shape or fashion for more than three decades. Texas development giant Hines, the tower’s developer, this week is unveiling the first look at 166 luxury condominiums on the upper floors of the 1-million-square-foot tower, perched atop 685,000 square feet of office space.

The world for these sort of skyscrapers has, of course, changed dramatically since South Station Tower closed on its $870 million construction loan and broke ground just before the COVID-19 pandemic began in 2020. And no, two years from the building’s completion, no leases have yet been signed for the office space. But Joe Norris, the managing director and project officer for Hines in Boston, is taking a glass-half-full view.

“This project is entirely unique in that its anchor is the largest transportation hub in New England,” Norris said. And though Boston’s office market is sluggish — like most other major metros across the United States — the majority of new office leases are landing in newly built or upgraded properties.

“Our position is that this is a world-class, mixed-use, transit-oriented development, and those types of projects will outperform,” Norris said. “If you’re going to have your employees come back to work in the office . . . you’re going to want that vibrant, mixed-use (environment).”

The tower’s 685,000 square feet of offices will start on the 11th floor, where Hines is also planning an outdoor park space designed by landscape architecture firm OJB. The lowest residential floor, meanwhile, will be 450 feet in the air. A 36th-level amenity floor will include indoor/outdoor space — including that western-facing pool and another terrace with space for outdoor cooking.

Architecture firm Pelli Clarke & Partners designed the glassy tower, whose 51 stories soar up from the classic facade of South Station. Fred Clarke, a partner at the firm, said in a statement the tower’s location exemplifies transit-oriented, urban development.

Construction on the tower above South Station.
Construction on the tower above South Station. SUZANNE KREITER/GLOBE STAFF

“The South Station complex will set the standard for an enlightened, transformative approach to urban living and working, and become a global model for responsible growth,” Clarke said in a statement.

Residential sales at the tower begin this fall. There’s already a “pretty reasonable waitlist” of potential buyers, including young professionals, couples, and empty nesters, said Sue Hawkes, managing director of luxury residential firm The Collaborative Cos. Many are attracted to the Ritz-Carlton brand.

“That flag is meaningful,” she said. “It resonates with people. It’s world-renowned. A flag in a building is definitely an uptick in value.”

Commercial office and residential uses complement the other, Hawkes said, because “they live at converse times,” and the chance to hop a train to New York right downstairs is particularly appealing to business executives who go back and forth between here and there.

“If you look at where amenities are going these days: bigger, better, best, always,” Hawkes said. “All these buildings and all the people who are paying the condo fees on the higher side have an expectation for service and amenities. They just do. And the buildings that have sold the quickest answer those calls.”

The 166 residential units range in size from under 1,000 square feet for studios and “junior one-bedrooms” to just under 4,000 square feet for duplex penthouses. Both Hawkes and Norris said it’s too early to be specific on pricing, but Hawkes added the building is “going to be competitive with the highest end in the city, for sure.”

The residences are scheduled to open in 2025. Beyond the office and residential tower, the first phase of the South Station project includes an expanded bus terminal and an upgraded train concourse. There are two additional phases to come — a residential or hotel building above the bus terminal expansion, and another 510,000 square feet of office and amenity space above the existing bus terminal. The three phases together are expected to add just under 2 million square feet of new space, along with 895 parking spaces.