Berlin – Every Berliner knows him. And millions of tourists have taken photos with a picture of him. His faded, larger-than-life-sized portrait has loomed for 25 years over Checkpoint Charlie, the historic U.S.-controlled border crossing that stood for three decades between West Berlin and the communist East.

The U.S. soldier has become a symbol of one of the most important moments in modern history: the fall of the Berlin Wall 30 years ago Saturday.

The soldier, former U.S. Sergeant Jeff Harper, came to the German capital when he was 22 to play the tuba for departing troops. While here, he was photographed by Frank Thiel, who took photos of the last Allied soldiers in Berlin in 1994. His portrait and an image of a Soviet soldier were later chosen to hang at Checkpoint Charlie to commemorate the border between the East and West.

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Harper retired in 2010 and now lives with his family in the American Midwest. But he hasn't forgotten the fateful night the Berlin wall came down 30 years ago. On November 9, 1989, the collapse of the wall shocked the world. It marked the beginning of the end of the Cold War and the fall of the Communist dictatorship in East Germany – paving the way for German reunification in 1990 and the collapse of the Soviet Union in 1991.

"I was at work," Harper recalled in an interview with CBS News. "It was a Thursday, I believe, and we'd heard that something was going on down by the Brandenburg Gate. So a bunch of us took the subway to the city center, and it was very surreal."

An image of Jeff Harper is seen behind two lamp posts on November 7, 2014 in Berlin, Germany. Adam Berry/Getty Images

"There were people starting to climb up onto the wall," he told CBS News. "We thought that was strange at the time. But then more and more people found their way up to the top, and so did we."

A day later, Harper found himself with a hammer on the Berlin Wall contributing to its demolition.

Now in his 50s, Harper said he feels proud and humbled to have played a small part in the formation of history, and he has no doubt as to what message that momentous occasion holds in history.

"I think humanity has a lot of good things when we work together," he said. "And of course this doesn't happen all the time, but I do feel for the German people and a significant historical event did happen and it gives me hope for the future — that no matter how difficult things may seem, the world can change in one night for the better."

Lessons from that era could also be learned by contemporary world leaders, Harper said. "I think that walls never solve anything," he says, referring to President Trump's plans for the U.S.-Mexico border.

The former soldier was no stranger to ceremony. He had been sent to Berlin to play in the 298th Army Band, the longest-serving unit in the West German city. The band would play at farewells of fellow GI comrades and perform at state receptions like the visit of future U.S. President Bill Clinton.

Jeff Harper

Although a friend who was stationed in Germany sent Harper a postcard featuring his picture in 1998, he was convinced it had been manipulated to contain his likeness.

He was oblivious to the portrait's prominence until he visited Berlin a year later. When he saw himself immortalized above the well-known crossing point, he was "shocked."

"I was proud to be representative, or at least my picture, of the significant events that happened there," Harper said.

The former man in uniform last visited Berlin 13 years ago, but has one wish for the site of his unexpected fame: to radiate dignity.

Last week, Berlin's authorities decided to ban actors from posing as American GIs at Checkpoint Charlie, a decision, Harper said is long overdue.

"It diminished what happened there. And it diminished the significance for the Allied powers and the German people. I'm glad to see them go," Harper said.

He said it "feels very strange to me, but in a good way, a proud way," to think of his portrait hanging over the historic site.