The Kennedy Center’s expansion project, now with a $250 million fundraising campaign, will open Sept. 7, 2019 — more than two years late and $100 million over its original cost.

Arts center officials offered the first glimpse of the building Tuesday at a hard-hat tour for community members. Under construction on 4.6 acres south of the original facility, the building will encourage interaction between artists and audiences with glass-walled classrooms and studios, Kennedy Center President Deborah Rutter said.

“There is no backstage space. It’s not like there’s a front of house and back of house,” Rutter said. “It’s, ‘We’re all in this together.’ ”

To be called the Reach, a name meant to inspire connection and evoke President John F. Kennedy’s aspirational leadership, the building is mostly underground but marked by three white concrete pavilions that dot the hill that slopes away from Edward Durell Stone’s 1971 building. Two levels of studios, rehearsal rooms and lobby spaces can be used for multiple purposes, including intimate performances, exhibitions, master classes and parties, Rutter said. An arts camp is planned starting in the summer of 2020.

The largest studio, which matches the size of the Opera House stage, will probably be used as a cabaret for much of the first year, she said. There is a 150-seat space that can screen films or host lectures or small concerts, and the Skylight Pavilion — with two walls of glass — may be used for concerts, parties or as a casual meeting place. There are also dedicated classrooms for students and teacher development, and a lab that will encourage artmaking.

Tuesday’s celebratory atmosphere belied the project’s many delays and cost overruns. A groundbreaking for the $100 million project was held at the end of 2014, before officials sought the required design approvals. Subsequent negotiations with the U.S. Commission of Fine Arts and the National Capital Planning Commission ended with a floating pavilion on the Potomac River being moved to land. Construction didn’t start until October 2015, the price tag grew to $175 million and opening was pushed back a year to 2018.

The discovery of hazardous soil and the decision to address issues related to D.C. Water’s Clean Rivers Project during construction — to minimize future work on the site — added to the delays. The design’s swooping concrete walls also proved a challenge, Rutter said, noting that design mock-ups took extra time and “a couple walls got knocked down and rebuilt.” As a result, the original opening date of May 29, 2017, will be missed by more than two years.

The original budget did not include about $20 million in “hidden costs” for fundraising, technical upgrades in the parking system and equipment costs, Rutter said. The new $250 million campaign goal is $75 million more than the $175 million in hand and includes programming funds. The project is being funded entirely with private donations, including a $50 million gift from Kennedy Center Chairman David M. Rubenstein.

“This is a gift to the country,” Rubenstein said about the space that honors the 35th president. “(Kennedy) really inspired me and my generation. Today we say thank you.”

About 100 donors, board members and civic and arts leaders took a hard-hat tour of the construction site, where students from the Duke Ellington School of the Arts, a local choir and a trio from the National Symphony Orchestra performed. Jason Moran, the arts center’s artistic director for jazz, played a grand piano.

“What a wonderful laboratory for the work to exist in,” Moran said about the building. “We’ll come to see the Reach as a testing ground for new ideas.”

Architect Steven Holl said the structure is about shaping spaces and fusing interiors with the outdoors. Visitors need to experience the 72,000 square feet of new interior space — with its concrete walls and terrazzo marble and cherry wood floors — to understand how it works it, he said.

“It’s all sculpted,” he said. “Most of the building is below grade, interconnected to the original building and the three pavilions, which are instruments to bring natural light to the spaces below.”

Holl said the landscape has been shaped around the building to increase natural light and to provide views of the river and other landmarks. There will be a reflecting pool, a grove of trees and a sloping lawn that will serve as an informal amphitheater for free simulcast screenings of performances going on inside the original theaters, he said.

“These are Kennedy-like dimensions,” he said. “Unlike the Lincoln or the Jefferson memorials, this is a living memorial. It’s all about the change and the future.”

Correction: An earlier version of this story described the expansion as having a $250 million price tag and being $150 million over budget. The expansion has a $250 million fundraising campaign, and the project is at least $100 million over its original cost. This story has been updated.