Demolition and abatement have already begun on the landmark Tishman Building on Lafayette Square, with new owner Hamister Group aiming to complete the conversion of the historic former National Fuel Gas Co. headquarters into a hotel, apartment and corporate offices by the third quarter of 2014, the project’s lead architect told Buffalo Place directors Wednesday.

Officials are seeking to restore the 53-year-old building to “what it looked like in 1959,” said Jonathan Morris, partner at architectural firm Carmina Wood Morris PC, which is coordinating the work for Hamister. “It will be spruced up, fixed up and look great.”

Plans for the $41 million project call for a Hilton Garden Inn hotel with 124 rooms to occupy the first 14 floors, with 18 market-rate apartments taking up floors 15 through 17 and Hamister’s headquarters moving to the top three floors from its current location in Amherst. The three floors of apartments will feature six units each, while the corporate offices will house 30 to 40 employees.

There will be a new entrance on Lafayette Square that will become the new entrance to the hotel, and the first floor will have the hotel lobby and dining space. Food service will be located on the second floor, meeting rooms on the third floor, and the guest rooms will start on the fourth floor. A pool and fitness center will be housed in the basement, Morris said.

Hamister has contracted for valet parking arrangements with several parking facilities.

Hamister plans to open the first-floor ceiling to the second floor and install light fixtures hanging through, Morris said.

Using Philadelphia-based Berkowitz Co., the firm plans to take a one-inch-thick, double-glazed insulated glass panel and adhere it to the existing glass, to provide a “triple-glaze” system, Morris said. That will save energy and costs in the long run, but allows them to leave the existing glass in place as required by its historic designation. The original glass will also be cleaned, he added.

All approvals are in place, including from the National Park Service and Hilton Worldwide, which had to agree to Hamister’s submission of an interior design and furniture package.

“We’re excited to see the project move forward,” said Buffalo Place Executive Director Michael Schmand.

Hamister had been dealing with one tenant on the third floor, information technology provider Shatter IT, which had a long-term lease and did not want to move because it has significant networking infrastructure set up.

But the parties negotiated a resolution, and Shatter IT consolidated to another site it has at Main Place. “That was a good thing because we were having to design around them,” Morris said.

Located at 10 Lafayette Square, the 20-story, 140,000-square-foot building, the 13th-tallest in Buffalo at 263 feet in height, was added to the National Register for Historic Places last year. To qualify for the listing, a building has to be at least 50 years old and meet one of four other criteria.

The building was originally designed, in the “International Style” of architecture, by New York City firm Emery Roth and Sons and was built by Tishman Realty & Construction, using concrete beams and columns rather than steel frames. Morris noted that Emery Roth’s “claim to fame” was post-World War II skyscrapers and office buildings, and this is one of the few Roth buildings outside of New York City that also retains its character. At the time, it was also the first new structure built in downtown Buffalo in 30 years.

The Tishman Building was the headquarters of National Fuel until the company moved to Amherst in 2003 and has been largely vacant since. It had been owned for years by the Lillian Goldman Family Trust LLC in New York, which sought unsuccessfully to find a new use or buyer.

Hamister, which had been exploring a different plan for its corporate offices with another developer, bought the building in May 2011, with plans for its mixed-use project using historic tax credits.