A woman in a flowered summer dress was tentatively playing Chopin in Tribeca Park at Beach Street and West Broadway. The piano, adorned with a collage of magazine cut-outs, stood back to back with a second piano, a baby-blue companion. Then the woman’s friend arrived and a flurry of competing notes swirled through the air.

“Do you know the blues?” asked the friend, Christian Oates.

“No,” said the woman, Mari Kamada. “You play something and I’ll play with you.”

For the next few minutes, as the two tried to figure out what to play, they got up and down and switched seats so many times that it looked like a Marx Brothers’ routine. She would play a few bars, he’d come sit next to her and watch. Then he’d go back to his side and she’d get shy and go watch him. Then they’d both head back to her side together. Eventually they gave up.

“She plays classical and I play jazz,” Oates explained. “Never the twain shall meet.”

For all the discordant meetings, there no doubt were countless harmonious ones. Plant a piano in the middle of the city, and relationships blossom all around it.

In Battery Park, a young tourist from Florida named Nicole Trejo played a moonlit ballad by the gothic rock group Evanescence. A seven-year-old girl named Margot conducted with a twig. Later, Margot and her friend Gianna sat side by side and improvised a duet, a roiling thunderstorm of smashed keys that Margot’s mother, a dance photographer, likened to Stravinsky. 

The two-week project that ended July 5, was sponsored by Sing for Hope, an organization that brings music into underserved schools and communities. In Lower Manhattan, Sing for Hope placed pianos in Tribeca Park, City Hall Park and Battery Park.

If you spent a few hours on a recent  afternoon in any of these places, and if you then compiled a program of the pieces you heard, it would have read, in part: “La Vie en Rose” (Piaf); “Nocturne” (Chopin); untitled jazz fantasy (Griswold).

Griswold? Scott Griswold is a professional set-dresser, but he could be seen in City Hall Park in sandals, shorts, and sunglasses, playing with his head down, eyes shut tight against the distractions of the world—cell-phone cameras, squirrels, a small crowd of tourists, camp kids and workers with ID cards clipped to their belts that gathered around.

The music was meditative, shimmering chords and cascading arpeggios, like the soundtrack to a corporate video about environmental responsibility.
“Something I made up,” Griswold said afterward, taking a drag of a cigarette with an air of studied casualness. A folded piece of paper peeked out of his shirt pocket. “I want to play all the pianos in Manhattan,” he said, “so I printed out a map.”

Back in the West Broadway triangle, after dusk, a 20-year-old and a man of about 40 jammed on a simple chord progression by Coldplay that the older man had never heard before. 

“Do you like the Grateful Dead?” asked the older man, Geoff Wilson, when the song was over.

“I’ve heard of them.”

Both Wilson and the younger man, Ed Arzomand, were newcomers to the city. Wilson, who owns a 7-11 store in Springfield, Mass., was in town just for the pianos. Earlier, at City Hall, he’d seen someone trying to teach himself the Charlie Brown theme song and showed him the proper key to play it in. They struck up a conversation and ended up strolling to Tribeca Park so they could play together on its two pianos.

They banged out a few classics—“Green Onions, ” “Like a Rolling Stone” —before Ed Arzomand jumped in.

He knew just one tune, the Coldplay one, but you didn’t have to be Fats Waller to get something out of the experience.

“I’ve only lived in the city for three weeks and I feel like there’s a lot of disconnectedness, but artistic expression gives people an opportunity to connect,” he said. “A momentary connection with a random human being is the most beautiful thing you can do.”