United Nations Secretary-General Ban Ki-moon(3rd L) symbolically turns on a switch at Empire State Building for the UN Blue campaign in New York, Oct. 23, 2015. From the Sydney Opera House in Australia to the Great Pyramids of Giza in Egypt, more than 200 of the world's most iconic landmarks will be lit United Nations blue when the sun sets on Oct. 24 to mark the 70th birthday of the global organization. (Xinhua/Li Muzi)
