A protester sprays paint on the window of a bank during a rally against Expo 2015 in Milan, Italy, April 30, 2015. The Milan Expo will open in the city on May 1. Officials are counting on some 20 million visitors to the six month-long exhibition of products and technologies from around the world. (Photo by Stefano Rellandini/Reuters)

A demonstrator holds a paint roller and a bucket during a protest against Expo 2015, in Milan, Thursday, April 30, 2015. Milan has been growing in altitude in preparation for Expo 2015 world's fair opening next Friday with the construction of a dozen new skyscrapers in recent years. City leaders hope a successful world's fair, expected to attract 20 million visitors over the six-month run, will help Italy's fashion and banking capital grow in international stature as well. (Photo by Riccardo De Luca/AP Photo)

Demonstrators attend a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

A man spatters paint on a shutter as he uses a fire extinguisher during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

A man uses his cell phone as he takes a selfie in front of a painted bank's showcase during a protest against Expo 2015, in Milan, Thursday, April 30, 2015. (Photo by Riccardo De Luca/AP Photo)

Demonstrators wearing dark hood on their head, fire flares during a demonstration in downtown Milan on April 30, 2015 to protest against the World Exposition Milano 2015 (Universal Exposition) saying that the massively indebted Italian state should not be ploughing money into an ephemeral event at a time of economic hardship for many Italians. The Expo will run from May 1st, 2015 to October 31, 2015 on the theme Feeding the Planet, Energy for Life. (Photo by Filippo Monteforte/AFP Photo)

Italian Carabinieri, paramilitary police officers, patrol in front of the Expo gate during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

Demonstrators write down the hashtag “1M No Expo” during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

Police in riot gear advance during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Riccardo De Luca/AP Photo)

Demonstrators climb the Expo gate during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

A man spatters paint on a shutter as he uses a fire extinguisher during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

Demonstrators gather at the Expo gate as a banner reads in Italian: “I don't work for Expo for free” during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

Demonstrators attend a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

Demonstrators climb the Expo gate during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

Demonstrators attend a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

A demonstrator attends a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

Police in riot gear advance during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Antonio Calanni/AP Photo)

A man hold a smoke flare during a protest against Expo 2015 in Milan, Italy, Thursday, April 30, 2015. (Photo by Luca Bruno/AP Photo)

A masked demonstrator sprays color on a shop door during a demonstration in downtown Milan on April 30, 2015 to protest against the World Exposition Milano 2015 (Universal Exposition) saying that the massively indebted Italian state should not be ploughing money into an ephemeral event at a time of economic hardship for many Italians. (Photo by Filippo Monteforte/AFP Photo)