LONDON — Europe's best known landmarks — including the Eiffel Tower, Big Ben and Rome's Colosseum — fell dark Saturday, following Sydney's Opera House and Beijing's Forbidden City.
Millions of people were turning off lights and appliances to mark the Earth Hour from 8:30 p.m. in a gesture to highlight environmental concerns and to call for a binding pact to cut greenhouse gas emissions.
As each time zone reached the appointed hour, skylines went dark and landmarks dimmed, from a Manila shopping mall to Berlin's Brandenburg Gate and the Empire State Building in New York.
About 4,000 cities in more than 120 countries — starting with the remote Chatham Islands off the coast of New Zealand — were voluntarily switching off, though traffic lights and other safety features were unaffected, organizers said.
"We have everyone from Casablanca to the safari camps of Namibia and Tanzania taking part," said Greg Bourne, CEO of World Wildlife Fund in Australia, which started Earth Hour in 2007 in Sydney before it spread to every continent.
In Europe, Italy's Leaning Tower of Pisa and buildings across Germany and a host of nations went dark. Amsterdam cut the lights at most city buildings including Schiphol Airport, Artis Zoo and the Amsterdam Arena.
While France's Eiffel Tower dimmed its lights only briefly for security reasons — five minutes, rather than a full hour — other city landmarks, including the Arc de Triomphe, were in darkness for the duration of the event.
Also joining in were Buckingham Palace, the British Parliament building and other famed London landmarks including St. Paul's Cathedral and the Royal Albert Hall, as well as Edinburgh Castle in Scotland.