It was a bright afternoon and Darius Cappelli, 18, made the trip down from Connecticut to play his banjo as part of Make Music New York, a day of impromptu concerts across the city.

He was sitting on a stepladder near Astor Place, playing a few Joshua “Peg Leg” Howell classics, when Isaac Gorrell, 21, of Stillwater, Okla., showed up with a banjo of his own.

The two didn’t know each other, but they played anyway, singing songs about gambling in the South.

“He lost his leg because of his gambling debts,” Mr. Cappelli, who wore part of a blue suit with a red hat and tie, said of Howell. “By the time he died, he had two peg legs.”

Mr. Gorrell, a student at Oklahoma State University, said he was staying at his brother’s apartment in the city for a month because “school’s out and I don’t like to work very much.” He found Mr. Cappelli, who recently graduated high school and is working odd jobs for the summer, in a schedule of musical events.

And so it went around the city as more than 560 concerts took place yesterday in venues ranging from Lincoln Center to a cemetery in the East Village. A saxophonist played a set outside Charlie “Yardbird” Parker’s old house and a robot guitar played itself on Third Avenue in Brooklyn as its creator looked on with pride.

The event was modeled after France’s “Fete de la Musique,” founded 25 years ago by the minister of culture at the time, Jack Lang. Mr. Lang was in town yesterday to witness New York’s version.

“The only rule is everything has to be free, open,” he said, as a slight breeze blew water from the fountain in Washington Park onto his gray suit. Two bands on opposite sides of the park competed for the attentions of passersby. “Every city finds its own genius, its own inspiration.”