By Laura McGuire The City will be plunged into darkness on Saturday as some of the capital’s most iconic landmarks turn off their lights to raise awareness for climate change. From 8:30pm, the Barbican Arts Centre, the Central Criminal Court, the City Corporation’s Guildhall headquarters, and the Mansion House will take fall dark in support of Earth Hour, the City of London Corporation has said. Tower Bridge, which is managed by the City Bridge Foundation, of which the City Corporation is sole trustee, will join them. Mary Durcan, chair of the corporation’s port health and environmental servic…