Underneath the complex's 40- -by-20-foot Jumbotron, children tossed footballs and sprinted about, while neighborhood residents and their dogs wandered through the square.
"Watching the game outside always adds a different dimension," said Andy Hurwitz, the Piazza's director of programming. "It makes it feel more interactive - it's the next best thing to being there."
There have already been concerts and movie nights at the Piazza, the 80,000-square-foot Northern Liberties development that opened in May, and there have been the weekly Tuesday Phillies' nights. But now the complex has added the Big Kahuna of Philly entertainment, NFL football, to the mix.
Yesterday, that mix also included a ton of food. There were grilled hot wings and sandwiches made with sausage and peppers, or roasted pork and provolone.
Valerie Morris, who works for Vino Restaurant and Lounge, served the goodies to customers from one of the ring of tents that Piazza management had set up and rented to the spectators. In a tent nearby, there were cigars.
Spectators were in high spirits. The Antonini family, for one, was celebrating the 95th birthday of Bianca Antonini, family matricarch and lifelong Eagles fan "since the first day."
When the Piazza paused during a break to sing "Happy Birthday" to Antonini, the retired tailor and seamstress responded with her own cheer, yelling "Go Eagles!" and pumping her fist into the air.
Yesterday, all eyes were on Eagles' backup quarterback Michael Vick, who was playing his first game after 18 months in prison for running dogfights.
"He deserves a second chance," said Karim Midhat. "He's one of the greatest athletes in the NFL."
Others weren't willing to forgive him so quickly. "He needs a visit from the Dog Whisperer," said Joe Morett, 31, who was at the game with the Antoninis.
By halftime the Piazza had filled in a bit - though there were still far fewer than the 980 visitors who had come for last week's loss to the New Orleans Saints, or the 600 who came for the season opener, according to Hurwitz.
The rainy weather stopped the Piazza from bringing a band to play on its stage, as it usually does, Hurwitz said.
He's hoping to keep the events going even as the weather cools, he said, with outdoor space heaters and enclosed tents.
"It's an easy way to watch the game," said Andy Riccardi, the Piazza's self-titled "mayor," who said the experience was for fans "looking for a different kind of place" to watch the game.
Not that there haven't been stressful moments.
"Two weeks ago, the sound dropped midway through the game, and our hearts stopped," Riccardi said. "But it was Fox," the TV network, he said, not the Piazza sound system.
Riccardi and Daniel Hoffman, the Piazza's technology specialist, controls the Jumbotron - and the remote.
Hoffman, who used to work at the Wachovia Center, operates the screen from a small room dominated by two towers of computers of input lines and gizmos.
"Twenty thousand people would be watching [at the Wachovia Center]," he said, "But it's more intimate [here]."
After the Eagles finally finished their 34-14 demolition of the Chiefs, Bianca Antonini said she was thrilled.
"It made my birthday," she said.