Youngsters attend the "workers' day concert" to celebrate Mayday in Rome's Piazza San GiovanniYoungsters attend the "workers' day concert" to celebrate Mayday in Rome's Piazza San GiovanniYoungsters attend the "workers' day concert" to celebrate Mayday in Rome's Piazza San GiovanniYoungsters attend the "workers' day concert" to celebrate Mayday in Rome's Piazza San Giovanni