Riot police walk past burning garbage containers during heavy clashes with demonstrators during a 24-hour strike on March 29, 2012 in Barcelona, Spain. Spanish workers staged a general strike to protest the government's latest labour reforms, which are designed to help Spain lower its deficit within EU limits. (Photo by David Ramos/Getty Images)

Demonstrators are seen running for shelter from a protest against plans for new austerity measures October 19, 2011 in Athens, Greece. Greece's largest labor unions have called for a 48-hour strike, while the Socialist government is beginning to push through legislation for cost cutting reforms. (Photo by Milos Bicanski/Getty Images)

“A Brazilian hotel was evacuated in the capital, Brasilia, on Monday after a man took hostage an employee who was held for hours before he was safely released to police. Firefighters and police cordoned off the area and about 300 guests and other employees left the hotel – some reportedly told to leave by the man who took the employee hostage”. – Associated Press. (Photo by Evaristo Sa/AFP Photo)

Construction continues on One World Trade Center (TALLEST BUILDING AT LOWER LEFT) as the memorial footprints of the twin towers are seen (BOTTOM C) on August 12, 2011 in New York City. Upon completion, One World Trade Center will be New York's tallest skyscraper, topping out at a symbolic 1,776 feet, with 3 million square feet of office space. More than 2,700 people were killed when al-Qaeda terrorists hijacked U.S. passenger jets and flew them into the twin towers of the World Trade Center on September 11, 2001. Nearly ten years after the crippling attacks on Lower Manhattan, business, tourism and new construction like One World Trade Center have rejuvenated the formerly devastated cityscape.(Photo by Mario Tama/Getty Images)

A fishmonger prepares fresh festive seafood supplies at the Sydney Seafood Market on December 23, 2011 in Sydney, Australia. The annual 36-hour seafood marathon commenced today with thousands of Sydney shoppers expected to flock to the Sydney Seafood Market to find the freshest possible seafood catch for Christmas Day feasts. (Photo by Brendon Thorne/Getty Images)

The Porsche 919 Hybrid No17 of the Porsche Team driven by Timo Bernhard of Germany is seen in action during the 83rd 24-hour Le Mans endurance race, in Le Mans, western France, Saturday, June 13, 2015. (AP Photo/David Vincent)

A general view of the Cathedral on the Blood on November 2, 2011 in Yekaterinburg, Russia. Yekaterinburg is one of thirteen cities proposed as a host city for 2018 FIFA World Cup in Russia. (Photo by Harry Engels/Getty Images)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)