(ANSA) - Rome, January 21 - Expo world's fair commissioner Giuseppe Sala pronounced himself optimistic Wednesday, 100 days ahead of the opening of the universal exhibition in Milan.
    "We will be ready," Sala said. "I urge the public to follow our progress on www.expo2015.org, which features drone footage of the infrastructure as it evolves".
    Some eight million tickets to the world's fair have been sold, with tourism to bring in an estimated five billion euros in related business, Sala said.
    "Participating countries have invested one million euros, 90% of which will go to Italian firms," the commissioner added.
    "Now it is time for ideas to regain center stage".
    Sala said 500 experts are slated to attend a pre-exhibition event to be held in Milan February 7 called Ideas Expo. Between them they will lay the groundwork for a Milan Charter, which will become "Expo's cultural heritage". This event will be promoted by Premier Matteo Renzi, Agriculture Minister Maurizio Martina and will include a video message from Pope Francis, titled "The Right to Food and Safeguarding the Earth".