For many middle and high schoolers, “To Kill A Mockingbird” by Harper Lee has been a cornerstone of their literary education. And now, the hit stage version made the move from the Broadway stage to Madison Square Garden, playing to a packed auditorium of New York students on Wednesday.

Roughly 18,000 young attendees, accompanied by their teachers and chaperones, gathered in the Garden, many of them seeing their first Broadway show. This landmark event marks the first time that a Broadway play has performed in the venue, and is now the most attended single performance of a play in a world theater.

Mayor Bill De Blasio and first lady Chirlane McCray came out for the occasion, along with filmmaker Spike Lee, who gave speeches that encouraged students to reach for their dreams and believe that they can make a change in society.

“Do not doubt the power of high school students, middle school students, all students who are right now in this city, in this country, around the world changing the way people think, changing what’s possible,” said De Blasio. “You are becoming the voices of conscience more and more in our society. You have to believe in yourself for us all to survive on this earth.”

Lee then took the stage, declaring that he is a product of the New York public school system, just like many of the children in the audience. He called the production a “historic moment,” and urged those in attendance to listen closely to the words of the play and to pursue their passions.

“Of the 20,000 kids, there’s gonna be somebody here today who says ‘I want to be a playwright'” he said, to which one student in the crowd yelled “Me!”

Before the show started, a local choir sang an uplifting rendition of “Rise Up” by Andra Day, and the audience waved their lit-up phones through the stands.

The performance, led by Ed Harris as Atticus Finch, was set on a 360-degree stage, unlike that of a traditional Broadway theater. The audience cheered when lawyer Finch stood up for his black client, Tom Robinson, wrongly accused of battery and rape, and gasped at the racist dialogue of some of the other characters who targeted him because of the color of his skin.

One high school student, 18-year-old Brianna Banful of Edward R. Murrow High School, told Variety that Lee’s novel, set in Alabama in 1934, is her favorite book, and Finch, her favorite character.

“I’m so excited to see my favorite characters come to life,” she said. “I specifically like Atticus Finch, just how strong he is even though the whole entire town closes themselves off from him just for defending Tom Robinson. I think the fact that he was able to go against it and stand up and do his job, I think that was the most inspiring thing.”

The free event enticed Laura Fries, 32, of LaGuardia High School to bring nearly 150 of her drama students to the Broadway adaptation. She said that she hopes the thematic elements of prejudice and racism will spark a larger conversation with her students.

“I just thought it would be very important to bring into my drama classroom and talk about it,” she said. “This is a bigger conversation about equity and about systemic problems in our country. It would lend its way nicely into the conversation now.”

“To Kill A Mockingbird” will go on a national tour starting in August. Greg Kinnear will take over the role of Atticus Finch starting in April. The show’s playwright, Aaron Sorkin, and producer Scott Rudin were also in attendance. In order to put on the event, executive chairman and CEO of The Madison Square Garden Company James L. Dolan donated the venue rent free as well as all in-house expenses.