Germany's reunification was one of the world's most daring multi-billion economic experiments. Yet 20 years after the fall of the Berlin Wall, the question remains: did it work?

Although the peaceful revolution of 1989 saw much of eastern Europe embrace the market, the formidable task of grafting one of the Soviet bloc's most regimented economies on to one of the west's biggest, most successful open markets had no equivalent.

This was a gigantic endeavour. Cost estimates for reunification range from €1,200bn ($1,780bn, ￡1,085bn) to €1,600bn, including direct subsidies to businesses, the rebuilding of the country's infrastructure and creation of a new political apparatus, plus welfare benefits for a large portion of 16.7m people living in the east in 1989.