As the sun rises at Tiananmen Square, protesters build a 10-meter (33-foot) Goddess of Democracy statue out of foam and paper-mache over a metal armature. In the early morning of June 4, soldiers backed by tanks and armored cars toppled the statue, which had stood directly facing the Mao portrait at the Forbidden City.

In the often tense days leading up to the Chinese government crackdown, local citizens often gave gifts to soldiers and police officials. Sometimes troops would sing patriotic songs with demonstrators. In this picture, a policewoman sings out loud in Tiananmen Square a few days before troops retook control of the area and crushed the democratic movement.

A woman is caught in the middle of a scuffle between pro-democracy protesters and People's Liberation Army soldiers near the Great Hall of The People on June 3, 1989, the day before one of the bloodiest military crackdowns of the 20th century. Later that night, the 38th Army would open fire on unarmed civilians overtaking the occupied Tiananmen Square.

Thousands of protesters surround a bus with a display of captured weapons just days prior to the crackdown. During the government's enforcement of martial law, soldiers and the public performed a delicate dance of give and take. Sometimes protesters offered gifts to soldiers and sometimes troops withdrew.

In the late evening of June 3, a group of protesters cornered an armored personnel carrier at the gates of the Great Hall of The People. It had just crashed through barricades of street dividers, which the crowds had put up to stop the advance of military vehicles. At the same time, soldiers were preparing to open fire on the demonstrators a short distance away.

On the late evening of June 3, protestors set fire to an armored personnel carrier on the Chang'an Avenue near Tiananmen Square. The picture was the last image before photographer Jeff Widener was struck in the face by a stray protestor brick. Though he sustained a serious concussion, The Nikon F3 titanium camera absorbed the blow sparing his life.

On June 4, a truck manned by People's Liberation Army troops patrol down the Chang'an Avenue in front of the Beijing Hotel the day after the bloody crackdown on student-led pro-democracy supporters. A similar truck full of soldiers had shot tourists standing in the lobby of the Beijing Hotel that day.

A lone man with shopping bags walks to the center of Beijing's Chang'an Avenue and temporarily stops the advance of Chinese tanks a day after the crackdown. Over two decades later, the fate of the man is still a mystery. The incident has come to symbolize the events at Tiananmen Square and is considered one of the most iconic images ever taken.

On June 5, a group of people at the Chang’an Avenue show a picture of protesters lying dead at a local morgue after having been shot by Chinese soldiers of the 38th Army during the recapture of Tiananmen Square. The troops used expanding bullets which created larger wounds. At least 300 civilians were killed, according to Amnesty International.

The remains of a burned-out bus on Beijing’s Chang’an Avenue as two women sweep up debris following the massacre. The demonstrations led to widespread burning of buses and military vehicles, which left several soldiers dead or injured.

Soldiers and a tank stand guard in front of the Forbidden City and across from the occupied Tiananmen Square a few days after the riots.

Associated Press photographers Jeff Widener (left) and Liu Heung Shing pose in front of Beijing's Forbidden City in late May 1989 just days before the Chinese government's military crackdown at Tiananmen Square.

This photo is a stark symbol of the peaceful Black Lives Matter protests in Baton Rouge, Louisiana. Fearless, wearing a long sundress, the 28-year-old New Yorker Ieshia Evans stands in the middle of the street, facing a group of heavily armed police officers. The photographer Jonathan Bachman was in the right place at the right time to take this picture.

Shopping bag in hand, an unidentified man stood in the path of tanks on Beijing's Tiananmen Square in June 1989, just a day after the Chinese military had used force to quash the protests. The lone protester later became known as Tank Man, the Unknown Protester and the Unknown Rebel.

In October 1967, 17-year-old Jan Rose Kasmir presented a chrysanthemum to the soldiers facing her in an anti-Vietnam War protest in Washington, DC. "These were just young men," Kasmir said in an interview years later. "They could have been my date, they could have been my brother. And they were also victims of this whole thing."

In downtown Montgomery in December 1955, Rosa Parks was asked to give up her seat as the bus she was riding filled up. She refused. "It was not that day or bus in particular," Parks said later. "I just wanted to be free, like everybody else," She was arrested. A citywide bus boycott lasted for more than a year - until the Supreme Court ruled that segregation on buses was illegal.

John Lennon and Yoko Ono held two nonviolent protest performances that lasted a week each, their famous 1969 bed-ins for peace in Amsterdam and in Montreal, Quebec. They invited the press and gave interviews about their protests against the Vietnam War.

On January 25, 2014, in Kyiv, an Orthodox priest said a prayer between lines of police and demonstrators. Ukraine's anti-government protests spread beyond the capital, with many people demanding that the country seek better relations with the European Union.

A police officer used pepper spray on Occupy demonstrators cowering on the ground at the University of California, Davis in 2011. The students were peacefully protesting a rise in tuition. John Pike lost his job, and the protesters received a settlement.

Endlessly shared on social media, the photo turned Ceyda Sungur in her bright red summer dress into a symbol of the anti-government Gezi Park protests in May 2013 after a riot policeman turned on her with a can of tear gas.

Seven bronze sculptures stand on a white stairway at the foot of the Prague Petřin Hill. Inaugurated in 2002, the memorial was originated by sculptor and former political prisoner Olbram Zoulbek. In the inscription of the pedestal it is not only dedicated to those, "imprisoned or executed but also for all those whose life was ruined by totalitarian despotism."

More than 11,000 people were imprisoned between 1951 and 1989 in the remand center of the GDR secret police (Stasi). Previously the grounds, in the Berlin neighborhood of Hohenschönhausen, were used by the Soviet occupying power as a special camp for alleged regime opponents. From there, the prisoners were transported to the Nazi-built concentration camp Sachsenhausen.

Since 2016, this 20-meter-high memorial made up of three wings by the sculptor Mihai Buculei has stood on the pedestal of a torn-down Lenin statue in Bucharest. It is situated in front of one of the most important buildings from the Stalin era, at Free Press Square. The initiative was the idea of the Association of Former Political Prisoners.

In Tirana, the first memorial after the overthrow of the Stalinist regimes was opened in 2017. During the Nazi era, the German occupiers had used the building as a prison. After the Communists came to power in 1945, people were tortured and killed here. Later the secret police used the "House of Leaves," which got its name because of the climbing plants on the exterior of the building.

In Gori, the birthplace of Joseph Stalin, the Soviet dictator still enjoys hero status in the museum named after him – 65 years after his death and 27 years after Georgia regained its independence. Currently there are plans to overhaul the exhibition. The crimes committed under Stalin have only been a central issue at the Georgian National Museum in Tbilisi since 2006.

Around 1.5 million Kazakhs fell victim to the famine of 1932/33, caused by mismanagement and forced collectivism. The sculpture ensemble in Astana is dedicated to the dead. It was inaugurated on 31 May 2012, the national day of remembrance to the victims of political repression.

"Milda" is the nickname given to the 19-meter-high obelisk of a woman’s enthroned figure in Riga. It was erected in the 1930s, before the Soviet occupation in 1940. The statue is the central memorial for Latvians for their will to freedom and self-determination. In past decades it has repeatedly served as the starting point for protests and resistance.

Located between Russia and China, Mongolia suffered under foreign occupation and exploitation for nearly all of the 20th century. For a long time, it was both politically and economically dependent on the Soviet Union. The museum to the memory of the victims of political repression was opened in 1996 in Ulan Bator; a year later, the memorial was added.

The bridge over the Imjin River, erected at the beginning of the 20th century, is the only bridge connecting North and South Korea. It was of great military importance during the 1950-1953 Korean War. On the southern side via a wooden pier you can reach the border. Many visitors leave flags and personal messages at this place.

An estimated 2.2 million Cambodians were killed during the terror regime of the Khmer Rouge. That was approximately half of the population. After the invasion, also by communist troops from Vietnam, human remains and skulls were publicly exhibited, in order to document the crimes. Even today, many mass graves have yet to be discovered.

This statue in Washington DC, inaugurated in 2007, is a replica of the "Goddess of Democracy" erected by Chinese students in 1989 during their fatal protests on Tiananmen Square in Beijing. Local politicians worked alongside eastern European freedom fighters such as Vaclav Havel and Lech Wałesa to erect this memorial in the US capital.

In 1940, Soviets murdered around 4,400 Polish prisoners of war – mainly officers – in a forest near the Russian village of Katyn. In Poland, the massacre is synonymous for a series of mass killings. The initiative for the memorial in New Jersey, which is dedicated to all the victims of Soviet communism, started with Polish migrants in the US.