Francis is set to arrive in Lisbon on Wednesday morning to celebrate World Youth Day, which is actually a week of religious, cultural and festive events held about every three years in a different city.
Images of the pope were on display on banners set up across the city as well as on screens on automatic bank machines along with the message: "I am with you".
A Lisbon pastry shop is even selling cookies with the image of the smiling pontiff wearing a crucifix.
"I think it is going to be an amazing experience to be in the same spot as the pope," Barbara Weisz said, a 19-year-old student from the United States, part of a group of 37 youths who came from a San Diego parish.
"It is a great feeling to be among so many young people who share your beliefs," she added as the group, who wore matching red t-shirts, gathered in the lobby of their hotel before going sightseeing and attending the opening mass.
World Youth Day, which has been dubbed the "Catholic Woodstock", is part of the Vatican's efforts to galvanise young Catholics at a time when secularism and disgust over clerical child sex abuse cause some faithful to abandon the Church.
