What happened on Bolyston Street the other day wasn't part of anyone's plan. A guy named Mark Copeland wandered past the Prudential Center to find some lunch, instead he discovered something he couldn't resist: a piano set up on the sidewalk.

"I was like, okay, let me see what's going on over here," said Copeland as took a break from playing a jazz rendition of Amazing Grace. Copeland is a professional musician, he teaches at Berklee College of Music and his impromptu performance struck a chord. A woman in a hard hat opened a door onto the sidewalk and started to dance. A mother angled a stroller so her toddler could watch Copeland play.

"This is great," said Copeland. "It relaxes everyone."

Sixty upright pianos have been rolled out into neighborhoods across Boston and Cambridge as part of a public art installation called "Play Me I'm Yours". Those words are hand-painted on every piano - an invitation to play.

"The nice thing about piano is, if your know a tune, you can kind of sit down and find the notes," explained Luke Jerram, as he picked out a melody on a piano installed on the Rose Kennedy Greenway.

Jerram dreamed up the idea of putting pianos in public spaces eight years ago when he was at a laundromat back home in Birmingham, England.

"I'd see the same people there every weekend, yet no one was talking to one another," recalled Jerram. "So I thought that by putting a piano in that location it would act as a catalyst for conversation."

The piano turned the laundromat into a performance space and started a street piano exhibition that has been replicated around the world. In each location artists hand paint pianos. The uprights around Boston include everything from Henna inspired designs to one that is covered with elements from the periodic table. There's even an upright covered with the image of Red Sox hitter David Ortiz. You can play the Big Poppy piano outside Fenway Park. No experience required.

"I've seen people sitting with a mobile phone teaching themselves how to play piano," said Jerram. "That's been really nice."

Jerram made a name not as a musician, but as a visual artist. His glass sculptures are on display in museums. Yet Jerram is passionate about bringing art outside, doing things like putting an orchestra in hot air balloons and pianos on city streets.

He says street pianos have helped professional pianists find producers, music lovers find each other. So what will happen here in Boston?

As he winds down his impromptu performance on Bolyston Street, Mark Copeland offers a hopeful note.

"Right now we need music in the world with what's going on," said Copeland."Yeah, this is going to bring us together."

Celebrity Series of Boston brought the street pianos to town as an encore performance. They were also installed around the city in 2013.