Venice, May 7 - The founder and owner of the Diesel clothing brand signed an agreement Tuesday to sponsor the restoration of Venice's iconic Rialto Bridge. The five-million-euro project will be overseen by Renzo Rosso's OTB holding company over the next 18 months, according to current plans, which were officially announced in December after years of rumors that Rosso, a native to the region around Venice, was eyeing the renovation. "I have to thank him on behalf of all Venetians, but also on behalf of the entire world, because maintaining this city is a commitment that goes beyond the city itself," said Venice Mayor Giorgio Orsoni. An estimated 20 million tourists trample Venice's ancient pavement every year, inevitably taking a toll on the 400-year-old Rialto Bridge, which for centuries was the only foot passage from one side of the Grand Canal to the other. In 2011 a column on the bridge's railing collapsed, and some of the marble steps have begun to crack, one of which was dislodged last summer, closing down part of the bridge. Calls for donors have become increasingly common across the country as city budgets have been cut amid Italy's economic crisis. In 2011 Diego Della Valle, the founder of the luxury leather goods brand Tod's, announced he was investing over 25 million euros in the three-year restoration of Rome's Colosseum, enlisting further help from the Italian business community to bankroll restoration and conservation plans elsewhere in the country in the absence of government support. The most visible example is perhaps French luxury-fashion mogul Francois Pinault, owner of such lines as Gucci, Balenciaga and Stella McCartney. Pinault made a splash in the Venice lagoon with the purchase of Palazzo Grassi, followed by the acquisition and restoration of the landmark Punta della Dogana, both of which house his personal art collection as well as featuring major exhibitions. Other fashion labels restoring sites in Venice include Bulgari, Replay and Palazzetti, in addition to Prada and Benetton who have recently bought palaces on the Grand Canal for private use. "When you make a profit, it's only right to give something back to culture and society, especially in times like these," said Rosso on Tuesday. "It's not the private sector trying to replace the State, it's the private sector trying to work with it in dialogue for the sake of a better world".