Anti-war demonstrators tried flower power on MPs blocking the Pentagon Building in Arlington, VA on October 26, 1967. It became a symbol of peaceful protest in the 60's.
Following a crackdown that resulted in the deaths of hundreds of student demonstrators in Beijing, a lone Chinese protester steps in front of People's Liberation Army tanks in Tiananmen Squarein 1989. At least five photographers captured the event, which became a symbol of defiance in the face of oppression.
The slideshow above displays some of the most iconic historical photographs, click on them to read more.
Prime Minister Mahinda Rajapaksa resigns amid raging public protest due to the ongoing economic crisis