University of Kansas Chancellor Bernadette Gray-Little signals to a crane operator to hoist a special signed beam to the top of KU's new Integrated Science Building to celebrate the university's Central District project, Thursday, Nov. 10, 2016.

More than 300 construction workers, University of Kansas VIPs and other guests gathered for lunch in a partially completed building Thursday, surrounded by massive cranes, gravel and bright orange temporary fences.

KU planned the event to celebrate a construction milestone — the “topping out” ceremony, in which the final beam is hoisted — for its new $117 million Integrated Science Building, considered the keystone of the university’s $350 million Central District redevelopment project.

“It’s not every day you get to celebrate the university’s largest expansion project in almost 100 years,” KU Chancellor Bernadette Gray-Little told the crowd.

Just a year ago, the Kansas Board of Regents approved KU’s construction and funding plan for the Central District project. It relies on a novel funding model called a public-private partnership, or P-3 for short, that raised concern among state legislators but that the university says will enable it to complete the massive project with little state funding.

Construction workers and other stakeholders sign the final beam of KU's new Integrated Science Building, under construction along Irving Hill Road, on Thursday, Nov. 10, 2016. The beam was later hoisted into place on the building as part of a topping

University of Kansas senior Laura Furney, of Wamego, signs a special beam to be hoisted to the top of KU's new Integrated Science Building to celebrate the university's Central District project, Thursday, Nov. 10, 2016.

Construction began shortly afterward, and by the time classes begin in fall 2018 — about two and a half years total — the area will be home to six new buildings. McCollum Hall, Stouffer Place apartments and the Burge Union have been torn down.

Central District work is on schedule so far, university spokesman Joe Monaco said. He said planned buildings and their completion dates are:

• Parking garage, early 2017

• Residence hall and dining facility, summer 2017

• Power plant, 2018

• New Burge Union, summer 2018

• Student apartment complex, July 2018

• Integrated Science Building, July 2018

“In 2014, KU launched a campus master plan, designed to put our aspirations as a flagship research university into physical form,” Gray-Little said. “Key to that plan was the development of our Central District into a new hub of education and research that would address urgent needs and position us for excellence for decades to come.”

The 28,000-square-foot Integrated Science Building, located on Irving Hill Road where the Burge Union formerly stood, aims to replace aging science facilities including Malott Hall.

Gray-Little said it would contain classroom and lab space for interdisciplinary research in chemistry, medicinal chemistry, physics, molecular biosciences and other fields. Importantly, she said, it would offer undergraduate students opportunity to collaborate with science research activity.

The Integrated Science Building is now framed in, though still without walls.

KU Dining Services employees grill hamburgers in plein air in the under-construction Integrated Science Building in KU's Central District on Thursday, Nov. 10, 2016. More than 300 construction workers and other stakeholders gathered for lunch and a topping

“The pressing need for science facilities has been a topic for KU for over 20 years, said university architect Jim Modig.

He said the new building’s design is centered around the concept of “science on display.”

Exterior and interior windows will let in daylight and provide views into labs, and there will be a central atrium, he said. Features will include a 325-student lecture hall, 18 classroom labs and 35 modular research labs.

The public-private partnership involves the KU Campus Development Corporation, a nonprofit corporation organized as an LLC that was created to enable the project. The corporation is working with Edgemoor Infrastructure and Real Estate LLC to oversee development, construction, operations and maintenance of the Central District property.

Officials with the main contractor firms for the Central District project, Clark Construction and McCownGordon, also spoke at the event, noting that there were currently about 300 construction workers on site and that at peak activity there would be about 600.

The Central District parking garage and new student union are taking shape just south of the Integrated Science Building.

The new residence hall and dining center, located behind Oliver Hall, is mostly enclosed. Foundation work has begun for the new student apartment complex, just up the hill at 19th Street and Ousdahl Road.

New roads providing access to the Central District — extensions of Ousdahl and 18th Street — and a large traffic circle have been completed, as well, with more to come.

Adjacent to the Central District, construction on the new Earth, Energy and Environment Center is well underway. Capitol Federal Hall, the new School of Business Building, and the DeBruce Center, which houses James Naismith’s original rules of “Basket Ball,” were completed and opened earlier this year.