Britney Spears to offer free Mexico City concert

US pop singer Britney Spears will deliver a free Christmas concert in a downtown Mexico City plaza, Mayor Marcelo Ebrard said. Spears will perform at the Monument to the Revolution on Sunday, kicking of Christmas festivities in the populous city, Ebrard said Tuesday. In late August 2009 some 11,600 volunteers set a Guinness world record by dancing the Michael Jackson song "Thriller" in unison at the Monument to the Revolution. Mexico City festivities include a giant Christmas tree; an ice rink at the Zocalo, the main city square; and artificial snow during a parade. The so-called "Princess of Pop" will also perform at concerts in the western city of Guadalajara on Friday, in Mexico City on Saturday, and in the northern city of Monterrey the following Tuesday.