"In this combo of two photos the illuminated ""New railroad bridge"" over Sava river, top, and a picture of the bridge with most of its lights turned off, are seen in Belgrade, Serbia, Saturday, March 23, 2013. Organised by the World Wide Fund for Nature, earth hour is observed every year to create awareness about conservation of energy and climate change. Around the world, people and organisations will be turning their lights off from 8:30 to 9:30 pm local time. (AP Photo/Darko Vojinovic)"
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