Launched in 1982, the "Fete de la Musique" has spread to more than 100 countries where the festival held on the day of the summer solstice has taken off.
Some 850 free concerts are planned across the globe in Brazzaville, New York, Hanoi and Beijing, mostly held at the local French cultural centres.
In France, the festival is celebrating 50 years of chanson francaise, with amateur and professional artists offering all-day free concerts in the streets, theatres, schools and local churches.
US singer Chris Isaak and British pop star Seal are headlining an evening concert in Paris's Bois de Boulogne, while the Paris orchestra is performing at the Louvre museum.
Some 2,600 police officers will be mobilised for the festival that runs until midnight.
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