The New York City-based owners of the HSBC tower have developed a preliminary plan, modeled after the John Hancock Center in Chicago, to redevelop Buffalo’s tallest building with a mix of luxury residences, offices and a hotel.

The plan, still in the early stages, would convert the 38-story tower into a mixed-use project, similar to what Uniland Development Co. did when it rebuilt the former Dulski Federal Office Building into the Avant.

The plan is a starting point for a panel of experts from the national Urban Land Institute who will advise on uses for the building, said Stephen Fitzmaurice, chief operating officer of Seneca One Realty, the building’s owner.

The land institute will send a team of real estate, finance, architectural and development experts to Buffalo Feb. 25-28 to meet a host of local leaders and explore options to redevelop the 850,000-square-foot building.

The tentative plan envisions luxury condominiums on the upper floors, offices in the middle and a hotel on the lower floors.

There would also be opportunity for more retail space and pedestrian access on the bottom plaza levels, since the departure of HSBC Bank USA could mean less need for extensive security, said David Stebbins, vice president of the Buffalo Urban Development Corp. and a local land institute member working with Fitzmaurice. A small grocery store is also possible, if there are enough local residents to support it.

Seneca One also wants to revisit the possibility of having a restaurant or banquet facility on the top floor, similar to what the building had years ago in space leased by Marine Midland Bank, HSBC’s predecessor.

Marine used the space to entertain clients and for internal functions but rented it out for weddings or other receptions on weekends, Fitzmaurice said. It was closed after Seneca One bought back the space for a tenant that needed a full floor.

A public restaurant might not be feasible, because it might not get enough daily use to support staffing and overhead, Fitzmaurice said. But a banquet facility could work because it would only need to be staffed when a function is booked. That’s similar to what is being proposed for One World Trade Center in New York City.

“You wouldn’t have to worry about getting enough functions,” he said, adding that Seneca One wanted the land institute to weigh in on the idea. “It’s a possibility. We think it would work here, but we want ULI to look at that.”

Finally, the restaurant or banquet facility would be combined with an observation deck directly below it, to insulate the luxury residences from the noise of any parties or events.

Fitzmaurice said the owners have also considered putting a private club up there that would collect dues to supplement food and beverage sales to make it sustainable.

“We’re extremely optimistic about the future,” Fitzmaurice said. “We want to do something that will be complementary to Canalside and hopefully something we haven’t seen before.”

He said the template for the overall plan is the John Hancock Center in Chicago, a 100-story, 1,127-foot-tall skyscraper that was built in 1970. It includes 700 luxury condos, 897,000 square feet of Class A office space and 172,000 square feet of retail space for Best Buy, Cheesecake Factory and others.

The project also has a restaurant and observatory on top, with plans for a skating rink.

Fitzmaurice noted that the Hancock Center and One World Trade Center in New York, also called the Freedom Tower, were designed by New York-based Skidmore, Owings & Merrill LLP – which also designed the HSBC tower. “They did a great job designing the building to begin with, which gives us great flexibility with different uses,” he said.

Seneca One is rethinking the tower because its three biggest tenants will have vacated by the end of next year, leaving it 90 percent empty.

HSBC, which has occupied most of the tower since it opened in 1972, will move its operations to the HSBC Atrium that it owns a block away and its former mortgage processing facility in Depew, which it leases.

Law firm Phillips Lytle LLP is relocating to the former Donovan State Office Building down the street, which is being converted into One Canalside. And the Canadian Consulate closed.

The city and Seneca One teamed up to bring the Urban Land Institute to town. A final report will take up to three months, Stebbins said.

“We’re looking for their guidance, but at the same time, it’s a pretty tall order for them to come in here and in the space of four days understand the area, understand our building and come back with recommendations,” Fitzmaurice said. “So we’ve put together what we think will work for the future and give them a starting point. We’re trying to do our best, and we’ll see what happens.”