It was the National Symphony Orchestra’s grand experiment.

Take the players far away from the hallowed halls of the Kennedy Center. Plop them in a high school auditorium in the socioeconomic stew that is Columbia Heights. Have them play some Dvorak, Debussy, Vivaldi. Then, observe: Who would show up? Would anyone?

Warren Williams, who manages community outreach for the orchestra, was nervous that Friday night earlier this month. Then he was amazed.

There were young black children, clinging to their parents. The local postman and some business owners were there, too. Thirty minutes before the performance, they waited in the hallway of Bell Multicultural High School along with an overwhelming mass of the skinny-jeaned, a line that stretched from the metal detectors at the entrance to the seats in the auditorium.

Over the past decade, much has been made of the transformation of Columbia Heights, thanks to the extension of Metro’s Green Line; the opening of big-box stores, such as Target; and a crop of new condos. Housing prices soared; young professionals moved in. Then came the inevitable tension between the working-class African Americans and Latinos who lived in the subsidized housing that once defined the neighborhood.

The NSO saw an opportunity and arranged a week’s worth of free performances and workshops at Bell and smaller venues. It especially set its sights on two of classical music’s most elusive audiences: minorities and young people.

“We thought here was a chance to reach out to everyone,” Williams said after the concert at Bell. “We know there are barriers to people enjoying classical music. But I think this shows that the music itself is not the barrier. We have to do a better job of reaching out.”

Orchestra officials and musicians plan to: They are thinking about expanding to other D.C. neighborhoods but haven’t chosen the next one yet.

As Williams spoke outside Bell’s auditorium after the concert, the orchestra’s assistant conductor walked by.

“That crowd — they were so young and so awesome!” exclaimed Ankush Kumar Bahl, himself only 34. “Let’s find a way we can keep them!”

The audiences were overwhelming: a standing-room-only crowd in the 850-seat auditorium at Bell and more than 5,000 music fans over the course of the week.

The symphony orchestra, whose 100 members see themselves as ambassadors to classical music, has long tried to shatter the porcelain image of symphony audiences being older — much older — by going to places where bands rarely touch Beethoven. Last year, it put on concerts and workshops in Kentucky; the year before, the members harmonized in West Virginia.

It wasn’t until last year that, in one of those “Why didn’t we think of this before?” moments, they thought about doing something similar in their own back yard. Columbia Heights seemed a natural place to start. Through two visits to classrooms at Bell and the attached Lincoln Multicultural Middle School, the staff had an affinity for the neighborhood.

As a business and retail enclave, Columbia Heights long had its own rhythm. Riots after the assassination of Martin Luther King Jr. led to decades of urban decay.

When John Chambers moved to Columbia Heights a decade ago, he never expected a heralded orchestra to embrace the neighborhood.

“To be frank, there just wouldn’t be enough white folks to raise interest,’’ he said. “The neighborhood needed this moment.”

Nowadays, parishioners at the Shrine of the Sacred Heart sing praises in English, Spanish and Haitian Creole. Inside the Wonderland Ballroom, indie pop rules. Inside Chambers’s own business, BloomBars, the sounds of hip-hop and neo soul resonate. All within 10 blocks.

“The flavor of Columbia Heights right now depends on who you ask,’’ Chambers said. “It’s hipster. It’s the ‘it neighborhood.’ It’s big business. It’s small businesses. It’s family owned. It’s community.”

Even so, advertising for the Bell concerts and smaller performances was limited. Word spread via Facebook and e-mail.

“I came because it was in my neighborhood,” said Rebeca Barge, 25, who works for a nonprofit education organization. “And I thought the entire thing was beautiful,” she said afterward.

Her friend Heather Rosner, a 27-year-old music teacher, interrupted her: “This helps break down barriers. This is usually seen as a thing for rich, white folks. But anyone can relate to this music.”

Some in the crowd clapped between movements in the pieces, even though in more-stately concert halls it’s considered a no-no. Some teared up at the beauty of Debussy’s “Clair de Lune.” They gasped at how loud the piccolo player piped during his big solo in “The Stars and Stripes Forever.” Some never stopped texting.

Two days later, a string quartet was stationed in BloomBars, Chambers’s performance space. They worked with local artists to fuse hip-hop with the music of Chevalier de Saint-George, a mixed-race French composer sometimes called the “black Mozart” who died more than three centuries ago.

On performance night, the room filled within 10 seconds. Almost 70 people bopped their heads as a singer and rapper turned lyrics about the composer, who spent his life trying to gain favor with the French nobility.

In the second row were two young children and their parents. Celia Bowker, 48, adores the symphony and attends frequently. But she was having a hard time persuading Tejas, 8, and Gwenith, 8, to stick with the cello and violin.

“I thought this was a chance to see the cello as something that can be cool and engaging and modern,” Bowker said.

That night, Tejas told his mom that he’d practice his cello a little more diligently. For that moment, at least, the fusion was complete.