Millennium Partners has redesigned its 1.6-million-square-foot Winthrop Square development with a distinctive new facade and a narrow glass walkway connecting two high-rises on the upper floors.

The latest designs drop the previous T-shaped office and condominium tower in favor of a “two-tower mentality,” Handel Architects’ Blake Middleton said during a presentation to a Boston Civic Design Commission subcommittee Tuesday. The two towers’ heights would top out at 691 and 613 feet, with a glass walkway connecting them from the podium up to 587 feet.

The new designs restore a pleated exterior near the top of the taller tower, which had been part of the original designs when Millennium was selected by the Boston Planning and Development Agency to redevelop the 1-acre site. Total residential space would decrease from 625,000 to 614,380 square feet, while the office space on the lower floors would total 684,965 square feet, up from 675,230.

“We appreciate this critique, and we hope we’re being responsible,” said Joseph Larkin, a principal at Millennium Partners.

Despite the changes, some members of the BCDC remained unsatisfied with the latest version.

“My concern is this is a site for one tower, not two. There’s a lot of volume we’re trying to put on this site,” commissioner Andrea Leers said. “It’s particularly painful from South Station.”

Commissioner Linda Eastley said the redesign is a “stunning solution,” particularly from the Winthrop Square side of the property.

“This is a huge improvement from what we saw last time. The difference in the materials is beautiful and the way the towers are joined makes more sense,” Eastley said.

But commissioner David Hacin said the scale of the project including the entrance to the first-floor “Great Hall” running between Federal and Devonshire streets could overwhelm the park in Winthrop Square.

“The language of the Great Hall feels like it reaches out and privatizes Winthrop Square. It throws the balance of the square off,” Hacin said.

Millennium and Handel said they’ll refine the designs and come back to the board for further review. Millennium Partners’ demolished the city-owned garage at 115 Federal St. last fall to make way for the project.