When the Berlin Wall went up overnight 50 years ago, the trapped East German enclave of Klein Glienicke became one of the most tightly guarded communities on the planet.
Due to quirks of geography and a tumultuous history, the horseshoe-shaped suburban area of 500 inhabitants was nearly surrounded by a wealthy part of West Berlin while it officially remained part of Potsdam in East Germany.
Residents of Klein Glienicke and their Western neighbours lived so close that they could look into each others' bedroom windows.
But even a friendly wave was "verboten", with the East Germans facing immediate expulsion from the idyllic district if caught in contact with the "enemy".
This proximity made it possible for dozens to flee exactly what the authorities hoped to stop by building the Wall and led to a decades-long crackdown that saw many of the original inhabitants swapped for true believers.
A quiet community of stately old Prussian houses, Klein Glienicke became a "special security zone" where streets never fell dark because of prison-style spotlights at the Wall that blazed through the night.
Life-long resident Gitta Heinrich watched the Wall go up and celebrated its fall on her birthday, no less in the picture postcard village on the Teltow Canal separating Berlin from Potsdam.
A far cry from normal small-town life, Heinrich recalls wild escapes, a shoot-out at the Wall and even a failed bomb attack against an East German officer.
"It was like living in a big jail," said Heinrich, 69.
"It was the smallest town (in East Germany) that was walled in in this way. You could not walk anywhere without bumping up against it."
She vividly remembers the sudden sealing of the border on August 13, 1961.
"We were so shocked the bridge was closed off, I couldn't get into town without my ID and my boyfriend couldn't enter at all," she said.
"At that point it was just a fence. It was worse when they built the concrete walls in 1965."
A playground for the rich and famous in the 1920s that attracted film stars from the nearby Babelsberg Studios where Marlene Dietrich launched her career, Klein Glienicke with the Wall quickly became a Cold War curiosity.
Today, there is little trace of the Wall but for the 50th anniversary, an exhibition at a nearby castle tells the remarkable story.
Curator Jens Arndt moved to Klein Glienicke from West Berlin 12 years ago. He said that before 1989, when the Wall fell, Westerners had little idea of what the mysterious town behind it was like.
"It was a tiny enclave embedded among 'the enemies of the people'," he said, referring to the capitalists on the Western side.
"East German soldiers said it was the most difficult part of East Berlin to secure."
The centrepiece of the exhibition is a model of the town built by the army to plan patrols and plot strategy to secure vulnerable sections of the Wall.
They had plenty of cause for concern.
Handymen and ambulance drivers often used the occasion of a job in Klein Glienicke to flee.
In 1968, a would-be refugee and an East German border guard with his own dreams of escaping, aged just 21 and 26, were both killed in a tragic shootout.
And in 1973, two families fled to the West via a 19-metre-long tunnel they dug from their basement using a child's toy shovel so as not to arouse suspicion.
That spectacular breakout led to regular cellar checks to prevent any similar attempts.
Heartbreaking photographs in the exhibition document a funeral in 1962.
A family, owners of the local butcher's shop, had fled Klein Glienicke for West Berlin in the 1950s but the clan's beloved grandmother stayed on.
When she died, the family was not allowed back for the burial so the service was held in Klein Glienicke at a church right next to the border, which at the time was closed only by a chain-link fence ringed with barbed wire.
Pictures show the mourners in West Berlin weeping on the other side of the fence, as the pastor speaks out loudly to be heard on both sides.
Anyone caught acting suspiciously could be cast out immediately, and found themselves quickly replaced by more "reliable" East German citizens.
"They had soldiers, customs agents, police officer and Stasi (secret service) people move in as residents were pushed out," Arndt said.
Heinrich worked as a gym teacher to avoid the ideological pitfalls but was occasionally called upon to take over a history class.
"When I was teaching the Nazi period I noticed frightening parallels in terms of surveillance of citizens," she said.
Heinrich said with a smile the fall of the Wall was "the greatest birthday present and it still is every year".
"But I am still learning what it means to be myself, without being afraid of the consequences."