Millions across the world lived in darkness for an hour on Saturday, participating in the 10th anniversary of Earth Hour. It is observed between 8.30 pm and 9.30 pm to highlight the need to protect the planet and spread awareness about climate change.

The initiative was introduced in 2007 by the World Wildlife Fund for Nature in Sydney, Australia, to protest against the spike in carbon dioxide emissions, driven by human activities, which has led to global warming. Since then, participation has spread to 7,000 cities in 172 countries.

Earth Hour is observed towards the end of March every year. It will be observed on March 31 next year.

A number of famous landmarks across the world were plunged into darkness to mark the hour, as well. Here are a few before and after views of Earth Hour as observed worldwide:

Chhatrapati Shivaji Terminus in Mumbai, India (Pic: Shailesh Andrade/Reuters)
Eiffel Tower in Paris, France (Pic: Philippe Wojazer/Reuters)
Kremlin in Moscow, Russia (Pic: Sergei Karpukhin/Reuters)
Tokyo Tower in Tokyo, Japan (Pic: Issei Kato/Reuters)
Opera House in Sydney, Australia (Pic: David Gray/Reuters)
Acropolis in Athens, Greece (Pic: Michalis Karagiannis/Reuters)