Perhaps because he lives a hundred meters from the Colosseum, always infested with tourists, the journalist and writer Marco de Eramo (Rome, 1947) has ended up dedicating an essay to him. The world's selfie (Anagrama; translated into Spanish by Xavier González Rovira) delves into "the most important industry of our time," in the author's words. "Just two centuries ago, no one could have foreseen that we would spend so much money and so much time traveling," he explains. According to Marco de Eramo, who recently visited the CCCB, tourism was made possible thanks to two revolutions: "The first, the technological revolution in transportation. The first person to dedicate a book to the experience of traveling on a cruise was Mark Twain. The innocents abroad [The Innocents Abroad] (1867-1869) is well worthwhile." The second revolution has to do with social conquests resulting from the class struggle: "If transport made it possible to move physically, paid free time and, later, the pension system made it possible for tourism to become democratized. It is important not to forget that tourism was the result of a political struggle. If at first only the elites could afford luxuries such as Grand Tour, tourism expanded to increasingly broader layers of society, until reaching the current tourism low cost".