Celebrations of German reunification are taking place to a background of mass refugee arrivals in Europe and particularly in Germany, the leading destination for people fleeing fighting and poverty in failed states in the Middle East for a better life in Europe.

The developments will further transform Germany, which has in recent decades turned into an open, multi-cultural society in which as much as a quarter of the population has migrant roots, Prinz said in an interview with the STA.

"Just take a look at the diversity of restaurants in Germany and you'll see that industrial exports are not our only export. We have become a much more open society than in the past."

She said that this was having major effects on the country and particularly its economy. "In the start-up industry in Berlin, for example, more than half of the companies are established by foreigners."

Just as reunification helped shape German development in the past quarter of a century, the current migration flows will also bring changes. "We will have to expand and upgrade our education system and build new apartments, since half of the refugees arriving in Germany are children."

Prinz assessed that the effects of reunification have been predominantly positive. "Infrastructure in the federal states in the east has been modernized. Cities such as Leipzig, Dresden and Berlin have become magnets for tourism and business."

Unemployment has also dropped to record levels in recent years, after hitting as much as 25% following restructuring of heavy industry and other non-competitive sectors in the 1990s.

This has required tough measure and has meant that some benefits have had to be shed and that the retirement age has been increased to 67. "Society is adapting a looking for new ways to strike a balance between work and leisure."

Moreover, extensive solidarity, including in the form of higher taxes and longer work weeks, has been needed to help the east develop after reunification.

The result of these efforts are mixed, with the new federal states making up ground on the old states in areas such as education and consumption, but still facing with lower pay. "As a result we're seeing migration from the east to the west, especially of young people," said the ambassador.

The east is therefore facing a bigger challenge with population ageing than the west, with the share of population above 40 in the former at 63% against 57% in the latter.

Regardless, the 25th anniversary of reunification is reason for celebration and for remembering the dangers of being forcefully divided by barbed wire, a lesson that applies also to modern challenges, Prinz told the STA.

"We must not forget borders can be overcome only through dialogue...and solidarity. It is our historic duty to promote the rule of law and a better future of all of us, including our neighbours, if we want to keep open borders."

For Prinz memories of reunification will have an enduring effect. "I'll never forget the photographs showing masses of ordinary citizens crossing the Berlin Wall because of a yearning for the rule of law and freedom."