It's not every day that you see this: A prepubescent girl in the middle of a Million Fan Mosh, squealing in apparent ecstasy and holding up a hand-drawn sign that declares "I (Heart) Linkin Park!!!!!!" A few feet to her left, a woman old enough to be her mother wearing a Toby Keith T-shirt. And nearby, a solemn-looking man holding his own stenciled statement that says: "Make Poverty History."

That unlikely brew of cause and cacophony was the hallmark of Live 8, the politically motivated pop festival that was staged Saturday in 10 cities around the world. The only U.S. edition was here, on the Benjamin Franklin Parkway in front of the Philadelphia Museum of Art.

Mayor John Street announced that 1 million people packed the 60 acres on and around the mile-long boulevard. If that number is remotely accurate, Live 8 would rank as the largest concert ever staged in North America.

No question, hundreds of thousands of people turned out for a musical smorgasbord that had the multiethnic rap-rockers Linkin Park and the country boy Keith sharing a stage with neosoul singer Alicia Keys, hair-metal relics Def Leppard and rap star Kanye West. (Not all at once, though.) United in cause, if nothing else, the disparate group of stars provided the draw -- and, every few minutes, the message, too:

Dear world leaders,

Rid Africa of debt. Now.

Signed,

The Billboard Top 40

"This is one of the most important things we will collectively or individually be a part of," singer Rob Thomas told the crowd. A sheepish look washing over his face, Thomas then introduced a relationship song by noting that "it doesn't have anything to do with" the issues at hand.

At least he acknowledged what was becoming increasingly obvious and awkward: That few of the performers chose material even remotely related to the core Live 8 message. Organizers did have the good sense to fill the show-closing slot with Stevie Wonder, who has long addressed human suffering and injustice in song; yet even Wonder's set included off-message love songs, such as "Signed, Sealed, Delivered I'm Yours."

The crowd was blessed with plenty of sunshine and relatively mild temperatures for July, although it didn't seem that way after a few hours in shoulder-to-shoulder formation. The show ran from a little before noon until nearly 7 p.m., about an hour longer than planned yet still relatively close to schedule for an event that came together in just 32 days.

By show's end, police reported four arrests for what were called minor incidents and five disorderly conduct citations. Thirty-eight people were transported to hospitals, primarily for heat-related problems, and about 300 concertgoers were treated and released at medical facilities at the concert site, according to Tom McNally, a spokesman for the city.

The technological difficulties of coordinating so many shows -- 10 on four continents -- became obvious early in the day, when the nine Jumbotrons in Philadelphia showed Paul McCartney and U2 performing "Sgt. Pepper's Lonely Hearts Club Band" in Hyde Park as audio bled in from Paris, where R&B singer Craig David was doing a severe disservice to the Beatles classic "Come Together." Throw in the distraction of a bass being sound-checked and you had a mash-up gone awry.

As if on cue, a mounted police officer's horse, trotting through the crowd, relieved itself at that very moment.

There were other glitches in Philadelphia, too. During the Black Eyed Peas' set, almost an entire verse of "Where Is the Love?" went unheard. Speakers popped and crackled during Destiny's Child's performance, appearing to strain under the weight of all that thunderous bass. (Or maybe that was the sound of all those jaws dropping when Beyonce Knowles sashayed onstage in a perilously short white skirt.)

The Jumbotrons were meant to connect concertgoers in the nether reaches of the parkway to the performers, but the screen operators often betrayed a wandering eye. The majority of West's electrifying set, for instance, was heard but not seen, as the screens flashed canned video images rather than the Chicago rapper-producer's actual performances of the smash hit "Jesus Walks" and the new anti-bling treatise, "Diamonds of Sierra Leone." It was a shame, as the set was one of the day's artistic high points.

Not that this was supposed to be about art.

Live 8 organizer Bob Geldof's goal was to make a social statement so grand, so loud, that the leaders of the industrialized world simply could not ignore it. So, with a few exceptions, Geldof booked the biggest artists, not necessarily the best.

How else to explain the ridiculous sight of Bon Jovi's Richie Sambora fretting over his anachronistic double-neck guitar? Or, worse: a choice slot for those piffle-rock masters, Maroon 5?

At least fans weren't ripped off. As with the other Live 8s, the Philadelphia concert was free.

"We're not asking for your money," actor Don Cheadle said from the stage. "We're asking for your voice."

Cheadle then urged everybody to sign an online petition to pressure the G-8 participants, meeting this week in Scotland, to help Africa out of abject poverty.

Said actor-rapper (and Philly native) Will Smith: "We're calling on the eight most powerful leaders to do what they can to end. This. Tragedy."

These being megalomaniacal pop stars, of course, there were also calls made in the name of far less noble causes.

Having been carried onto the stage on a throne, Smith instructed the crowd to scream "Will's house!" every time he asked just where we were. He also detonated various pyrotechnics in an apparent effort to mark his territory. (It didn't work, as he was overshadowed by several artists, including West, the rock-rap group Linkin Park performing an explosive set with rap icon Jay-Z; Australian heartthrob Keith Urban, whose country-pop performance was a revelation -- even Bon Jovi.)

The Black Eyed Peas weren't nearly as braggadocious as Smith. That's never been the boho-pop-rap group's style. The group did, however, show off at least a hint of crassness when lead vocalist will.i.am introduced the last part of the group's set by saying: "We're going to do a song off our new record, 'Monkey Business.' " In mentioning their product by name, the Peas stood virtually alone.

To their credit, the Peas -- like the other Live 8 performers here and around the world -- did not receive a penny for having performed. But it wasn't exactly a net loss. The artists got to perform their hit songs -- typically three to a set -- before a global TV audience that organizers predicted would number more than 2 billion.

Backstage, according to the Philadelphia Inquirer, every performer received a token of the organizers' appreciation: a $3,000 Hugo Boss duffel bag, along with access to an impressive spread of swag, from $2,000 Gibson guitars to Bertolucci watches worth as much as $6,000.

Backstage, in the press tent, celebrities were shuttled in and out for a little picture-taking and a little espousing about the troubled state of affairs on the African continent.

Some didn't even bother with the espousing part. There was Anna Nicole Smith, she of the hyper-inflated chest and the newly Trimspa'd bod. It was announced that Ms. Smith would not be fielding questions. She was, however, more than happy to provide a photo op. Dressed in skinny jeans and a nearly absent pink top, she preened and posed, smiling and mute, her Mystic Tan gleaming. She shimmied and shook her implants, just as Jumbotrons began transmitting Will Smith's speech.

"Every three seconds, a child in Africa dies," he intoned onstage as the other Smith shook her investments.

The Rev. Al -- Sharpton, not Green -- was in the house, seemingly impervious to the heat with his shellacked hair and beige leisure suit. He came with a posse and an agenda: He and Mayor Street would be meeting the next day to form a "follow-up plan" to Live 8.

Someone from the press corps wanted to know how Sharpton remained so "fearless."

"You have to be committed," Sharpton said. "You have to be here for a reason, not just a season. I'm not always fearless."

Rita Marley, looking glam and way younger than her sixtysomething years in high heels and capris, was channeling her late husband, reggae giant Bob Marley. When asked a question, she spoke in lyric:

"Get up, stand up, stand up for your rights," she said, "Get up, stand up, don't give up the fight."

Kami, the HIV-positive puppet who appears on the South African version of "Sesame Street," was backstage, too. Reporters diligently asked the puppet questions and jotted down answers.

Out front, the show began 15 minutes before noon, when the British band Kaiser Chiefs bounded onstage after what seemed like endless hours of sound checks. Looking like they'd time-traveled from the first Live Aid (neck scarves! oh-so-'80s blazers! rolled-up jeans!), the group offered a rather ominous opener: "I Predict a Riot."

If nothing else, the show suggested a possible new Olympic sport: The 60-acre steeplechase. Police cleared the parkway overnight and kept eager fans at bay until daybreak, when the tree-lined boulevard was reopened to pedestrian traffic and a human autobahn materialized. "It was crazy -- totally insane," said Michael Lunt.

The 23-year-old had flown in from Salt Lake City overnight, arriving just in time to make a mad dash in the general direction of the stage. To get there, he had to avoid wires, fencing, vending trucks, 400 Port-a-Potties and tens of thousands of people along the way.

"There were already a ton of people here," said Lunt's friend, Jeff Johnson, 24, who had taken the train up from Washington's Union Station. "The floodgates opened, and everybody just started running. Whoever was fastest got up to the front."

The two Brigham Young University students must be fleet afoot, then: As the show began, Lunt and Johnson were positioned just behind the metal barricades 30 yards from the stage. They were the best spots in the house, at least for the hoi polloi. VIPs occupied the area immediately in front of the 60-by-120-foot stage and even got their own folding chairs.

Lunt and Johnson hadn't slept since Thursday, and they clearly hadn't prepared for the marathon event. Neither was wearing sunscreen (which became evident by noon, as their faces turned a bright pink). Nor had they eaten since Friday, when Lunt had a small bag of pretzels on the plane and Johnson had a hot dog -- and now there was no food within grabbing distance. "We'll feed off the music, I guess," Lunt said.

And then, there was the bathroom issue. As in: how to go without losing those spots near the stage?

"We're pretty much stuck here," Johnson said. "I guess we'll have to go easy on the water. But it's worth it. It's a once-in-a-lifetime opportunity."

As fans wedged onto the parkway sang along to Destiny's Child's "Say My Name," a couple performed an erotic pas de deux, grinding to the music as the man yelled, "Owwwwww! Owwwwwww!" and others looked on in bemusement. There were those who attempted to picnic, bravely spreading out blankets on the grass -- only to have them trampled by the crowd.

As Wonder closed the show, the air was ripe with the fragrant aroma of day-long sweat and sunburned skin. Everyone got to their feet.Young girls swathed in the latest in boho-chic peasant skirts clutched tiny American flags. A contingent of rollerbladers danced with their helmets on. They'd been on hand to help, running water to police and firefighters. Now they were taking advantage of their access to get closer to the stage.

Backstage, singer Sarah McLachlan said that performing here was almost a "meditative" experience. "I've never gone by myself live in front of all these people," she said. "I almost started crying."

She said that as soon as she heard "a hint of a whisper" that Live 8 might be happening, she asked her manager to sign her up.

Wonder was the last to speak backstage, switching to a business suit emblazoned with gold brocade, evocative of Michael Jackson's court attire.

"How can you take the first continent of civilization, with all its natural resources, and not give back?" he said. "It's a joke."

Kerry Mann and thousands of others were stoked at the Philadelphia leg of the Live 8 concert to stamp out poverty in Africa.