In HBO’s pilot series, Treme, there’s a subtle storyline that viewers unfamiliar with the aftermath of Hurricane Katrina may be missing.

Congo Square—an area in Treme, La.’s Louis Armstrong State Park where enslaved Africans were allowed to gather on Sunday afternoons and practice cultural rituals like dancing and singing—has long been considered the city’s spiritual center.  Today, musicians still go there to play.

When Ghanaian musician Yacub Addy visited New Orleans in the 1980s, he could easily trace the roots of the music he heard there to African music.

“When I was there, I felt like I was still in Africa,” says Addy.  “The way I see the people second lining reminds me of the dance they do in Ghana—a similar thing with the umbrella called Kolomashi.  I said I have to take this thing from New Orleans to Ghana.”

He and Wynton Marsalis did just that: They combined their music and musicians to bring New Orleans to Africa and Africa to New Orleans at Congo Square.  The groundbreaking joint venture was supposed to debut at Lincoln Center, but just four days after the announcement, Hurricane Katrina hit.  This setback just strengthened their resolve. At Congo Square, nine months after the disaster on April 23, 2006, the free concert featured a song blending New Orleans second line with the Ghanaian Ga tribe’s traditional Kolomashi processional—a form of protest music.  The piece is about diverse people coming together, family, the individual will to freedom, war and peace, and understanding different ways of hearing. Part of this collaboration can be heard in HBO’s teaser trailer for the series.

Addy and Marsalis’ collaboration serves as a testament to that fact that in New Orleans, music is an extension of everyday life. For the outsider, it’s an experience of other-worldliness bearing witness to a culture that has thrived in its isolation. It’s a unique place where an impromptu party (or second line) can spark to life at any given moment and in any location (even a parking lot). Visitors are often mesmerized.  Especially because in New Orleans, the songs never end.