SOMETHING odd is happening to the cities of eastern Germany. Plattenbauten, the soulless prefabricated apartment blocks thrown up by the region's former communist rulers, are being knocked down. Occasionally one will be truncated, shorn of its upper storeys. Older streets are gap-toothed where wreckers have removed abandoned houses. Cityscapes are being pruned, removing dead and dying edifices in the hope of saving the rest.

City planners, normally keen to promote the building of homes, factories and roads, are responding to a double demographic crisis: the collapse of communist-era industry, which sent workers, especially young women, fleeing westwards; and a sharp decline in the birth rate.

Saxony-Anhalt, cradle of the Reformation and of East Germany's chemical industry, lost a fifth of its 2.9m people in the 16 years after Germany's unification in 1990. By 2025 it expects to lose nearly half a million more. In Köthen, where Johann Sebastian Bach composed the Brandenburg Concertos, so many young workers have left that “the population pyramid has become a mushroom”, says Ina Rauer of the town's building department.

The cities of the east no longer imagine they can avoid demographic decline. Instead they seek to manage its consequences, and a few are inventing ways to shrink gracefully. Saxony-Anhalt, which suffered an acute shortage of apartments in communist times, has now destroyed some 45,000 homes with federal help.

The infrastructure that served now-defunct factories and empty apartment blocks must be ripped up too. “Streets cost an unbelievable amount of money,” not to mention water pipes and electric cabling, grumbles Klaus Bekierz, who works for the building department of Dessau, half-an-hour's drive from Köthen. Its population has shrunk by a fifth to 76,000 since the early 1990s. “We can't pay for infrastructure for 100,000 people,” he says.

Urban attrition is frightening those left behind, bringing the threat of blight and crime. Eastern cities are courting industry, but capital is footloose and productive new factories employ hundreds rather than the thousands who once manned East Germany's behemoths. “It's not clear what the recipe for success is,” says Hans-Joachim Bürkner of Potsdam University.

That may account for the spirit of zany experimentalism that prevails in cities such as Dessau and Köthen. Under the motto “city islands”, Dessau is nudging life and commerce towards “core areas”, which means making a verdant city (which is already three-quarters parkland) even greener.

Traces of Dessau's busier past—a disused tower for smoking sausages or a dairy's chimney now occupied by storks—are being preserved. Parts of the void are being parcelled into “claims” of 400 square metres, which citizens can use free of charge for projects such as growing biomass for fuel. “Where buildings fall, gardens rise,” a hopeful billboard claims.

Köthen is diversifying beyond Bach to Samuel Hahnemann, the father of homeopathy. The house where he practised his treatment methods in the 1820s and 1830s still stands as a museum. A disused monastery will house a homeopathic library and an eastern German university may soon teach homeopathy in Köthen. Restaurants have already benefited from the extra traffic this attracts, reckons the mayor, Kurt-Jürgen Zander.

Köthen city even employs homeopaths to help provide what it hopes is a more holistic approach to curing the city's ills. On their advice, the municipality sought to prepare the residents of down-at-heel Ludwigstrasse for the demolition of 15 buildings by conducting painstaking interviews to find out how they thought the newly-created space should be used. To provoke a sharper reaction, the city dimmed the street lights, highlighting only the buildings designated for sacrifice. That “was a shock”, says one Ludwigstrasse resident, and it sparked off the dialogue the city fathers wanted.

The façade of things to come

Dessau and Köthen are drawing inspiration from the Internationale Bauausstellung (IBA) 2010, a project dreamt up at the Bauhaus Foundation in Dessau, which occupies the building where Walter Gropius and friends helped pioneer the stark geometrical Bauhaus style in the 1920s.

Such “building exhibitions” are a German tradition, held when social and economic change demands new ways of using space. Omar Akbar, the Bauhaus's director, sees IBA 2010 as a “laboratory” for coping with demographic decline that will one day afflict other cities in the industrialised world. He says the aim is to shape the process of urban contraction, rather than “merely let it happen”.

But IBA 2010 does not just bring cities extra fame and money (around €150m or $235m, largely from the federal and state governments). Its organisers also want to cultivate intangible qualities, like greater public involvement and a sense of distinctive identity for each community.

The town of Aschersleben filled the gaps along its ring road with large attention-grabbing posters (see picture above). And unlike its picturesque neighbours, Stassfurt now has a lake instead of its old city centre; the 15th-century church, town hall and 850 other buildings collapsed or were knocked down because of subsidence, caused by decades of mining to extract potash.

From the death of cities, the hope is that new life will emerge.