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.
A nation-wide state of emergency persists in Kazakhstan, following a week of violent protests and civil unrest