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Earth Hour: Lights turned off at world famous landmarks to raise awareness about climate change as Big Ben, the Sydney Opera House and the Eiffel Tower are plunged into darkness Many of the world's most famous landmarks were plunged into darkness to mark Earth Hour, a global campaign to highlight climate change. Stunning pictures show the before and during of stunning sites including Big Ben, Tower Bridge, the Empire State Building and the Sydney Opera House. The Earth Hour entered its tenth year this year. Last year 178 countries participated with 400 iconic landmarks going dark to support the WWF campaign. Read more: http://www.dailymail.co.uk/news/article-4349868/Global-landmarks-plunged-darkness-Earth-Hour.html Follow us: @MailOnline on Twitter | DailyMail on Facebook