One group of ancient stones is under threat from another, fear authorities in Rome, as the Rolling Stones prepare for a huge concert among the "very fragile" ruins of Italy's capital. The iconic British rockers are set to play to 65,000 fans in the Eternal City on June 22 at the Circus Maximus, the ancient Roman chariot racing stadium. The coming influx of spectators has raised concerns among heritage groups, who warned of "unpredictable consequences" and possible "acts of vandalism" in a "very fragile" area. "The choice of the Circus Maximus for the Rolling Stones concert brings a measure of risk for the heritage of the area that is not only heightened but also hard to predict," said the office of archaeological supervisors in a statement. They have called for an "extraordinary security plan" to be put in place to protect historical sites. It is not only the Rolling Stones that are bringing huge crowds to the city, however. The canonisation of two former popes -- Jean Paul II et Jean XXIII -- on April 27 is expected to bring as many as two or three million people to Rome. None of this has Mayor Ignazio Marino -- himself a Rolling Stones fan -- unconcerned. In a letter published on Sunday in the daily Repubblica, the leftist mayor said the chance to hear "the passionate chords of their rock in the archaeological heart of the city will be yet another demonstration of 'the great beauty' of Rome." His mention of the 'the great beauty' -- or 'la grande bellezza' -- bore reminders of the recent Paolo Sorrentino film of the same name, which won the Academy Award for best foreign language picture earlier this month. The film became a major talking point for the chattering classes in Rome with its depiction of a decadent and bored elite, obsessed with looking back to grander days. The government hopes that the Rolling Stones concert can turn into a full weekend of cultural events that will help rejuvenate the staid reputation of the city, while also providing a much-needed economic boost. The Roman chamber of commerce predicts that the canonisations and the concert could see the influx of tourists rise to 40 million this year, up from 35 million in 2013.