Berlin, Germany - In September 1964, Dr Martin Luther King travelled to Germany to deliver a sermon to Berliners who, three years before, had seen their city divided by a wall.



During his relatively undocumented trip, he spoke in front of a few thousand people in West Berlin about reconciliation, before making a surprise visit to the eastern side to make a similar speech. Drawing parallels between the civil rights struggle and what Berliners were facing, he said: "We have journeyed and suffered through the wilderness of segregation. For the first time, we stand on the mountain looking into the promised land of creative, integrated living. But there are giants in that land."



The "giants in the land" King once spoke of could today refer to Donald Trump's proposed wall on the border between the United States and Mexico. Trump wants to extend the existing wall to 1,000 miles of the 2,000 mile-long border. Trump has said it will be an "impenetrable" and "beautiful" structure that will curtail illegal immigration from Mexico into the US. Critics, however, have called it a "racist monument" that is divisive and offensive.

READ MORE: Building Trump's border wall

Germany was split for nearly 50 years, with Berlin and its wall coming to symbolise the division between Eastern and Western Europe. As the new US administration begins to make its plan a reality, some Berliners say that the legacy of their wall, and the suffering it caused, should serve as a powerful reminder as to why walls shouldn't be built. Such physical structures, many argue, are detrimental to society's progress, and go against the right to freedom of movement. The separation of families is one of the harshest consequences of them.

Marcus Schinkel is one of the children of the divided era. Schinkel, the oldest of four, lived with his priest father and his mother 50 metres from the wall in the eastern district of Mitte. He was 10 years old when the wall was taken down, and remembers a childhood of divisions and dreamlands.



Now 37, the actor and musician told Al Jazeera: "Three minutes walk from the home was this big wall. The other side always looked so colourful. But we knew this wall was not made to protect us, it was against us."



Schinkel's maternal grandmother escaped when his mother was still in school. The police gave her a choice: to either declare her mother officially dead or leave school. So she left school, making it difficult for her to get a decent job.



"I knew that this wall meant that I would never see my grandma," Schinkel says. "The GDR [German Democratic Republic, or East Germany] allowed short-term family visits and my mother would try and get through to see her mum. The officers would talk to her for hours, and she would come back crying. Two weeks later, it would be the same situation. She had four children at home who could never be sure if she was going to come back. No grandma, a stressed mother and the wall. This was our reality."

READ MORE: Voices from the border - Opposing Trump's wall

Originally from the south of Berlin, Angelika Hecker and her pregnant mother were evacuated from the city during the second world war to a town near Dresden, which later fell behind the "Iron Curtain", the Western European term for travel restrictions placed on Eastern Europeans during the Cold War. In 1957, 19-year-old Hecker and her younger brother escaped, joined by her mother and sister on the same day. Even though she fled four years before the wall was erected, a border was already in place, and Hecker says she felt the effect of living under strict rules that restricted where she could go.

Initially living as a refugee in the West, Hecker embraced being in the so-called "free world" and forged a successful career in medicine, becoming a neurologist and paediatrician. "Walls split society," she says. "Some people are kept outside, others are kept on the inside. And the reality is, walls won't stop people from trying to get through. People are saying Trump's wall is a terrible idea from an economic point of view. But I think this is a mistake from a moral perspective."



Walls have played a big part in Nataly Jung-Hwa Han's life. Her parents moved to Seoul before Korea split and she was born nine years after the separation, in 1962. As far back as she can remember, she knew that a division existed in her country and that close family members - her aunts, uncles and grandparents, who she still knows very little about - were living on the other side. In 1978, her mother was accepted into a programme for nurses in Germany, so they moved to the divided nation.

Han, the editor of Korea Forum magazine and a programme manager at an organisation for Korean-German cooperation, says: "The first time I entered Berlin was by car via the East. My heart was pumping so much. It's the kind of feeling I imagined having if I was entering North Korea."



Han, now 55 years old, moved to West Berlin two years before the wall came down and witnessed its fall. It made her think a lot about the possibility of unification in her home country, and the effect walls have on how people view each other.



"Walls create an economic imbalance between people, which can lead to racism and discrimination," she says. "South Koreans think North Koreans are poor and hungry, and are always fearing that they will come and take away what they have built. Any division can create prejudices."

These prejudices can remain even once a wall is dismantled, making it harder for society to move forward.

Simona Cannetti, 46, was one of the many people from outside the country drawn to Berlin after reunification. Moving from Italy to study German, she quickly immersed herself in a city that was embracing its newfound freedom. But as an outsider looking in, she was able to notice the scars left by the wall. "I could see discrimination coming from both sides," she says. "People from the West thought that East Berliners were badly dressed and were not open-minded. People from the East, meanwhile, thought that Westerners were arrogant capitalistas."



"Trump says this wall will protect people, but walls bring fear no matter what side you are on. Fear of the other is one of the lasting impacts of a separation wall," she adds.



Although there are profound differences between the two cases, there are also parallels to be drawn between the Berlin Wall and the one on the US-Mexico border. Schinkel says it would be wise to heed history's lessons.



"The GDR built the wall to make a jail. But Trump wants to keep people out," says Schinkel. "I believe any separation of 'I'm better than you' is a mistake. Any sort of division creates misunderstandings and a cruel situation. Freedom is the most important thing."