Speaking at a symposium near the Brandenburg Gate on Saturday, former Soviet leader Mikhail Gorbachev warned that the world was "on the brink of a new Cold War" and strongly criticised the West for having sown the seeds of the current crisis by mishandling the fallout from the collapse of the Iron Curtain.
"Instead of building new mechanisms and institutions of European security and pursuing a major demilitarisation of European politics ... the West, and particularly the United States, declared victory in the Cold War," said the man behind the Soviet Union's glasnost and perestroika reforms.
"Euphoria and triumphalism went to the heads of Western leaders. Taking advantage of Russia's weakening and the lack of a counterweight, they claimed monopoly leadership and domination in the world."
The enlargement of Nato, Kosovo, missile defence plans and wars in the Middle East had led to a "collapse of trust", said Gorbachev, now 83. "To put it metaphorically, a blister has now turned into a bloody, festering wound."
Previously an outspoken critic of Vladimir Putin, Gorbachev backed the Russian President's stance over Ukraine, urging Western leaders to "consider carefully" Putin's recent remarks at the Valdai forum: "Despite the harshness of his criticism of the West, and of the United States in particular, I see in his speech a desire to find a way to lower tensions and ultimately to build a new basis for partnership."
Such strong words of criticism, voiced by the man still affectionately known as "Gorby" to many in Germany came at the end of a week which saw the value of the rouble tumbling dramatically as a result of Western sanctions.
Saturday saw another reminder of the old east-west tensions still running through Germany when the usually rather staid proceedings of the Bundestag were shaken up by a musical guest performance. Veteran songwriter Wolf Biermann, who was kicked out of the GDR (German Democratic Republic) in 1976, performed a protest song called Ermutigung (Encouragement) and took a number of swipes at politicians from Die Linke (the Left party), successors to East Germany's ruling party, the SED.
"Your punishment is to have to listen to me here - enjoy," Biermann said, while gesturing towards the leftwing parliamentarians. He went on to describe Die Linke MPs as "dragon spawn" and "the miserable dregs of something that has luckily been overcome".
Only last week German President Joachim Gauck, a former head of the Stasi archives, had questioned whether the Left party had "really distanced itself from the ideas the SED once had about repression of people". Die Linke is on the verge of gaining its first state Premier, in the Thuringia region, something Gauck said "people of my age who lived through the GDR find quite hard to accept".
At least 138 people died trying to cross the inner-German border in the capital, more than 1000 in the country as a whole, in the postwar years.
German Chancellor Angela Merkel, who grew up in East Germany, attended a memorial concert at the Berliner Ensemble, and yesterday opened a new exhibition centre at Bernauer Strasse, near the Bornholmer Strasse checkpoint where as a 35-year-old she crossed over to the West for the first time. "I think you never forget how you felt that day - at least I will never forget it,"she said recently. "I had to wait 35 years for that feeling of liberty. It changed my life."
Balloon wall symbol of revolution
Berlin's new wall has taken far longer to erect than the one it commemorates.
The original wall, a barbed-wire line in the road at first then a fence and finally a guarded and fortified concrete partition, appeared almost overnight in August 1961; then, in a confused series of events 25 years ago today that are still misunderstood, turned suddenly porous and, amid quite extraordinary scenes, was torn down.
Berliners and the world at large have been sharing remarkable pictures taken from the air of their new wall, a line of 8000 illuminated white helium balloons. The installation, by artist Christopher Bauder and his filmmaker brother Marc, traces the old border between east and west. Today the biodegradeable balloons will be released into the air and once again the wall will disappear.
It was at a live televised news conference in the wake of growing civil unrest that in the early evening of November 9, 1989, Gunter Schabowski, a spokesman for the East German Politburo, said East Germans could begin to travel to West Germany and West Berlin. When questioned on the crucial detail of when this would be permitted, he unconvincingly replied: "To my knowledge, this is immediately, without delay."
But nobody had told the Berlin Wall's border guards, who were suddenly faced with mass crowds at the checkpoints. Shortly before midnight, still desperately awaiting orders to the contrary, one guard, Harald Jager, ordered his gate open at Bornholmer Strasse. Eventually they all fell, and a great event that wasn't quite supposed to have happened had happened.
Unlike the original wall, Berlin bureaucracy meant that the Lichtgrenze (Lightborder) installation took the Bauder brothers seven years to bring to completion. The line of balloons leads past the obvious places: Checkpoint Charlie, the Brandenburg Gate.
Yesterday, a little boy rode his bicycle down the Zimmerstrasse where the tourists gather, slaloming in and out of the balloons, crossing the old partition about once every four seconds, becoming shy when half the queue for the museum turned their filming iPhones on his unknowingly poignant stunt.
But the balloons also stretch out into some quite ordinary areas, and have given many ordinary Berliners an extraordinary history lesson. On a nondescript patch of grass in the Gesundbrunnen district yesterday, Isi Gersten, a 24-year-old jewellery designer, was throwing her stick high over the partition while her labrador darted across to the other side to fetch it.
"It's funny, isn't it?" she said. "We come here every day and do the same. When this [new] wall arrived, it just made me think, gosh, you know. I knew it was along here, but didn't know it was right here."
At various points, television screens play specially commissioned films from around communist Eastern Europe, as a reminder that the wall that made West Berlin an island was merely the most potent symbol of the much larger Iron Curtain that divided east from west - a structure that also crumbled in those heady months in 1989.
By the Brandenburg Gate, where the biggest of these screens sits, hundreds of Germans and lots of tourists have been standing in silence watching films.
One shows East German refugees clambering over the walls of the West German Embassy in Prague, where they briefly lived in fear and squalor.
Another shows families of Hungarians rushing for a gap in the border that had suddenly opened up, with only the clothes they were wearing but with broad smiles on their faces and babies in their arms.
5 Things to watch for
1 Two million expected
At least two million people were expected to attend a grand street festival at the Brandenburg Gate today.
2 Gorbachev to take stage
The former Polish President Lech Walesa, Hungarian ex-President Miklos Nemeth, as well as former Soviet leader Mikhail Gorbachev and German President Joachim Gauck, are all expected to take to the stage.
3 Classics and rock
Music will be provided by the Berlin State Orchestra, conducted by Daniel Barenboim, as well as East Berlin rock band Silly and British singer-songwriter Peter Gabriel, performing David Bowie's Heroes.
4 8000 balloons
White balloons numbering 8000 have been pegged to the ground along the former border. They light up to form a 15km-long "wall of light". Today the balloons will be released into the air one by one, to the music of Beethoven's Ode to Joy.
5 Guests of honour
Berlin Mayor Klaus Wowereit, as well as guests of honour including Nobel Peace Prize winner Muhammad Yunus, Nasa astronaut Ron Garan and Wikipedia founder Jimmy Wales, will start the balloon release at 7am NZT.
- Observer, Independent