Jay-Z, Rihanna, J. Cole & More Attend Barclays Center's 40/40 Club Launch

September 27: Rihanna and J. Cole attend the grand opening of the 40/40 Club at Barclays Center in Brooklyn, New York.

Walking up to the calm, subdued exterior of the Barclays Center last night (Sept. 27), it was hard not to imagine the madhouse it will be tonight, when Jay-Z formally opens the House That Jay Built with his first of a string of eight concerts ("Eight shows for H.O.," as he put it).

"I walked around here earlier and I just seen everybody busy and at work trying to finish up, and it was a great feeling," Jay-Z said as he stopped briefly on the red carpet before moving on and refusing more interview requests. "A guy stopped me in the hallway and said, 'Man, this is a great thing for New York City.' And that's what the whole thing was about."

But the grand opening of the Barclays Center's 40/40 Club -- Hov's chain of nightclubs that includes spots in Las Vegas, Manhattan, and Atlantic City -- was a much more intimate kick-off event, though no less celebratory. And with attendees such as Jay, Rihanna, J. Cole, ?uestlove, Brooklyn Nets players Deron Williams, Joe Johnson, Reggie Evans, Jerry Stackhouse, and Josh Childress, and the New York Knicks' Amare Stoudemire, to name a few, the place wasn't lacking in star power.

But with Jay-Z involved, the event never is. The 40/40 club is a classy, largely open space, with an entire wall that gives way to a view of the court -- or, in last night's case, the stage and seating setup for Jay-Z's upcoming residency. Guests took advantage of an open bar that included Jay-Z's line of cognac, D'ussé (by Bacardi), which launched earlier this year, and select burgers, crab cakes, and chocolate-covered strawberries. There was some conversation about the club's sleek look and design, which borrows much from its Manhattan cousin, and the new arena in general, which casts an imposing glance down Atlantic Avenue with its impressive girth.

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But the biggest thing on anyone's mind was the excitement building over Jay's string of shows. ?uestlove, who has performed with Jay several times in the past -- most notably at his Carnegie Hall shows earlier this year -- said he'll be working this week on Jimmy Fallon and wouldn't make it out until the final show on Oct. 6. "The first night is all about filling the house," he said. "The last night is going to be the best."

Today's big opening of the Barclays Center brings its week-long unveiling to a close with a celebration of the borough it calls home and an eight night run from the rapper that helped bring Brooklyn its first professional sports team since 1957. As the night wound down, DJ SNS began spinning Rihanna's new single "Diamonds" and, fittingly for the occasion, Jay-Z's own "Empire State of Mind."