Big plans and high prices are changing an area of the city artists claimed once the Wall came down
From a height of more than 200m above Alexanderplatz, the revolving restaurant on Berlin's TV Tower offers a God's-eye view of one of the world's greatest experiments in urban design.
The vista that inches past diners shows a city heart that beats again after four decades in Cold War suspension.
Gleaming, sharp-edged offices, apartments, shops and cinemas fill Potsdamer Platz, the square that before World War II was Berlin's Piccadilly Circus. By the Brandenburg Gate stand the embassies of Britain, France and the United States. Where Hitler's chancellery once stood, Germany's federal states have built offices in glass and stone.
Next to parliament - the Reichstag renovated by Norman Foster - is the new chancellery building. On a bank of the River Spree, reaching out to walkers, cyclists and river steamers, the glass-fronted building is a stunning combination of confidence, modesty and openness.
Rebuilding Berlin's Government, diplomatic and commercial core was an enormous undertaking which required tens of billions of euros and transformed the city into Europe's biggest building site for a decade.
Underpinning the transformation was a long debate in which the public shaped decisions in favour of low-rise buildings, social housing, public transport and cycle paths.
But, in some ways, this was the easy part, for it entailed building on land that was empty, scraped clean to create the Wall's death strip.
A tougher task now faces Berlin as it contemplates what to do with Mitte, the old city centre and former heart of the once communist-ruled eastern half. As it does so, conflicting voices are being raised, touching on the very identity of the city itself.
Some are warning that Mitte, with Alexanderplatz at its heart, is being destroyed by too many offices, department stores and hotels and that Berlin's edgy lifestyle is being sucked out by gentrification. Others say the rebuilding approach is too timid, lacking the dramatic buildings that are a signature of New York, London, Shanghai and other cities.
"The architecture of individual buildings and the individual quality of buildings built around Alexanderplatz is probably without exception bad," says Berlin town planner Ares Kalandides. "The first thing Alexanderplatz needs, and most architects agree upon, is it needs to be densified. I would love to have a gentrified area of shops, but that is not going to happen because this is a place dominated by malls and large department stores."
Kalandides' links with the city date back to pre-unification days when he worked alongside West Berlin's urban planning senator, so he is aware of the city's sensitive history and the pull of bygone days. In his novel Berlin Alexanderplatz, Alfred Doeblin wrote of a city with a tapestry of differing lives and numerous strands and facades.
After the Wall fell in November 1989, artists moved into Mitte, using decrepit or abandoned buildings as studios, galleries or bars. Now only a few are left, the rest forced out by higher rents or court rulings.
Last month, C/O Berlin, a photography gallery implanted in a former post office in Oranienburger Strasse, was given its marching orders. The building has been bought by an Israeli investment group, Elad, a company that converted New York's Plaza Hotel into luxury apartments. Elad wants to turn the property into a hotel and shopping centre.
A short distance away lies Tacheles, a former department store squatted in by underground artists for two decades. The outside walls are pocked with bullet holes from April 1945 and its inside walls are smothered in layers of graffiti. The courtyard is covered in a beach of sand, a makeshift bar and an exhibition of large rusting sculptures.
In June, Tacheles' co-operative staged a demonstration to fight eviction by a bank which is owed money by the building's owner. The site alone is estimated to be worth €70 million ($125.3 million).
"Berlin is changing in a negative way, and it's not just about Tacheles, there is a force out there trying to destroy this city's freedom," Spanish-born artist Txus Parras said. Parras is just one of thousands of artists who have been drawn to Berlin since the Wall fell in 1989.
In bohemian strongholds such as Kreuzberg, reaction to the perceived invasion of "Schicki-Mickis" (yuppies) has at times been more than verbal.
Anarchist groups have targeted luxury cars, torching more than 270 in 2009. In 2007, after a private members' club, Soho House, which caters for the media elite, announced it would open an upmarket hotel in Prenzlauer Berg, a district neighbouring Mitte, the facade of the Bauhaus building was spray-painted with "No Exclusive Club."
Another question, though, is what to do with the architectural legacies in East Berlin from the 1945-89 communist area. Few people have come forward to plead for their protection on the grounds of beauty or historic value.
East Germany's parliament building, the Palace of the Republic, a 1970s orange-glass monster dubbed the "Lampenladen" (lamp shop) by Berliners because it had so many lightbulbs, was ripped down with little ceremony in 2008. The plan was to replace it with a reconstruction of an 18th century palace that was heavily damaged in World War II and eventually demolished. But Berlin, nursing €60 billion in debts and 15 per cent unemployment, has put the scheme on hold.
The money squeeze and resistance to prestige projects weigh especially on Alexanderplatz, a square with huge historic resonance.
In its heyday in the 1920s and 30s, the "Alex" was a beehive that inspired an expressionist novel and two films. After the war, it was disastrously rebuilt by the communists, expanded to the equivalent of 10 football pitches and surrounded by shoddy Stalinist-style office and apartment blocks. Its windswept, rain-stained expanse has a grubby, unwanted feel and a reputation as a haunt for drug dealing.
In the early 1990s, plans were made to erase many of the concrete blocks and build a cluster of 150m-high skyscrapers. But the scheme was pared back, saving a long row of existing apartment buildings, reducing the height of the skyscrapers and slowing the pace of construction. In the meantime, another vast department store, called the Alexa, has been built on it.
Hans Kollhoff, an architect who co-authored the original plan for Alexanderplatz, says "narrow-mindedness" is killing a unique chance to make Berlin the world's architectural wonder.
"It's depressing to see what's happening in Berlin at the moment," he told the Tagesspiegel daily last week. "It's cheap, cheap, cheap - the most basic stuff you can imagine."
According to architectural historian Paul Sigel, Alexanderplatz is a site with complex and contradictory strands.
"Although the place seems to be completely modern, there are deep layers of history ... If there would be a great architectural idea such as the Eiffel Tower people could discuss it, identify with the idea or refuse it. But unfortunately there is currently no real great idea for the Alexanderplatz."
