BERLIN — On Monday, Berliners celebrated a once unthinkable occasion: The Berlin Wall has now been gone for longer than it stood. But on the same day, the city's authorities confirmed the discovery of a previously unreported stretch of the wall in the district of Pankow in northern Berlin.

It had already been discovered by a man named Christian Bormann in 1999, but the now-37-year-old Berlin resident kept his discovery a secret for almost 20 years as German authorities kept erasing more and more remnants of the city's division.

“Berlin wasn't ready for this discovery when I came across it,” Bormann told The Washington Post.

In the years following Germany's reunification in 1990, the Berlin Wall was deeply loathed, and most of it was immediately demolished. Only a few sections, including the famous East Side Gallery in central Berlin, remained intact. Bormann knew that if he had publicly revealed his discovery in 1999, it probably would have been torn down. "But now, 20 years on, people realize how significant this discovery really is,” he said.

Bormann initially faced scrutiny by authorities and the media over his claim that the 260-foot stretch of the wall — publicized on his blog in mid-January — was once part of the first Berlin Wall, hastily erected in 1961 after East Germans were barred from leaving their country. When East Germany later decided to make the barrier more permanent, it expanded provisional brick walls into massive concrete barriers with watchtowers and mines. Many of the initial parts of the wall were destroyed in the process, but one appears to have survived in Pankow.

Bormann's discovery is now drawing tourists and locals alike, even though the area has since been fenced off for preservation work.

Discovering forgotten parts of the Berlin Wall has become a difficult but not impossible task. Confirmation of Bormann's find came only weeks after construction workers discovered a hidden tunnel once used by East Germans to flee to West Berlin.

More than 100,000 East Germans tried to do so between 1961 and 1989, when it came down. At least 270 of them died trying to cross the border — East German soldiers were instructed to fire at any of their compatriots who attempted to escape the politically repressive and economically bankrupt system.

Yet many former East Germans — born in a country that no longer exists — still have mainly positive memories of that era. Along with strict political control and pervasive surveillance, they also recall a country in which women received the same pay and had the same responsibilities as their male co-workers, and in which — at least according to official statistics — unemployment was nonexistent.

Former Post foreign correspondents Robert McCartney and Marc Fisher look back at the fall of the Berlin Wall in this video produced for the 25th anniversary. (Davin Coburn and Gillian Brockell/The Washington Post)

Those multifaceted memories usually reemerge most vividly in Berlin, where East and West Germans lived separate lives for decades — and where reminders of the separation are still all around. A photo of the city taken by Dutch astronaut André Kuipers from the International Space Station in 2012 showed one such reminder: The yellow-tinged lights mark the former East Berlin, while the whiter fluorescent lights favored by the West Berlin government show the other half of the city.

Somewhere along that dividing line of light, in the upper part of the photo, 260 forgotten feet of the Berlin Wall were still standing when the photo was taken. It took six more years and an amateur historian for Berlin's hidden wall to reemerge.

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President Ronald Reagan delivered his "Berlin Wall" speech on June 12, 1987 in West Berlin at the base of the Brandenburg Gate. (Reagan Foundation)