NB Development Group has refinanced its debt on two buildings within the 15-acre Boston Landing mixed-use development in Brighton.

Wells Fargo provided 10-year financing for 15 and 20 Guest St., which contain a combined 359,000 square feet of commercial space.

The 228,901-square-foot former New Balance headquarters at 20 Guest St. is being renovated for the new headquarters of Harvard Business Publishing which will relocate from 300 North Beacon St. in Watertown.

The location at 15 Guest St. contains a parking garage and retail space, including a Newbury Comics, NB Fitness Club and a New Balance store.

The existing debt on the property was $56 million, according to Suffolk County Registry of Deeds records. Transwestern | RBJ arranged the refinancing.

The transaction gives NB Development more flexibility as it moves ahead with future phases of the 1.8-million-square-foot Boston Landing project, said Chris Skeffington, senior vice president of capital markets with Transwestern | RBJ.

“The cost of debt today is as low as it’s ever been and that’s been a theme for two or three years,” Skeffington said. “NB Development plans to hold onto everything in the campus long-term. It’s long-term financing, and so they are able to put it in the drawer and not think about it for a while.”

Skeffington and Transwestern | RBJ Partners Steve Purpura and Chris McCauley, as well as Vice President Andrew Stone, worked on the transaction with Jim Halliday, managing director at NB Development Group, and Kevin Doyle, treasurer at New Balance.

NB Development completed the first phase of the $500 million development, the 250,000-square-foot New Balance headquarters, in September.

The project also includes construction of 80 Guest St., containing the Warrior Ice Arena, which will become the new practice facility for the Boston Bruins, and a 119,000-square-foot office building. The combined structure is expected to be complete in September.

The next phase will include 295 apartments at 125 Guest St. The developers also have permits to build an additional 460,000 square feet of office or R&D space, which are being marketed on a build-to-suit basis.

Boston-based HYM Investment Group is partnering with NB Development on the project overlooking the Massachusetts Turnpike and served by a new MBTA commuter rail station scheduled for completion this year.

In a separate transaction, Transwestern | RBJ has placed a 10-year acquisition loan with Blue Hills Bank for acquisition of a two-building portfolio at 68-78 Elm St. in Hopkinton by NorthBridge CRE Advisors LLC of Boston.

Transwestern | RBJ’s Skeffington, Andrew Stone and Roy Sandeman arranged the financing, working with Dean Atkins and Greg Lauze, principals at NorthBridge.