The population of Austria's capital is forecast to grow by 20 per cent to nearly two million people by 2031, compared with just under 2 per cent population growth predicted for the European Union as a whole.
And similar to the eve of the First World War, when Emperor Franz Joseph I ruled Austria-Hungary, half the population will be first- or second-generation immigrants, according to Gustav Lebhart, a researcher at Austria's statistics office and co-author of a new study.
"History is sort of repeating itself," Mr Lebhart said.
"Around the turn of the 20th century, in the imperial age, Vienna also had some two million inhabitants, and half of them had an immigration background as well."
Convoys of buses carry commuters daily in and out of Vienna - the city is just an hour's drive from the Czech Republic, Slovakia and Hungary, and closer as the crow flies to Ukraine than to Austria's western border with Switzerland.
The coming wave will change the face of Vienna's immigrant population, currently dominated by Turks - many of whom came for work in the 1960s - and people from the former Yugoslavia, both seeking work and fleeing the 1990s civil wars.
However, while the Turkish community is visible in parts of Vienna like the Ottakring district, where Turkish fruit stalls dominate the market, eastern Europeans tend more to blend in - much as they did in the past.
The new forecast puts Vienna among the ten fastest-growing European regions, in a league with flourishing areas in Ireland and parts of the Netherlands and Spain, ahead of the shrinking countries from which many of the new Viennese originate.
The expected shift in immigration comes after Austrian companies, especially banks, acquired a series of companies in eastern Europe and have transformed Vienna into a regional commercial hub over the past 15 years.
Austria shielded itself against a glut of cheap labour with transient quotas for workers and bans on self-employed craftsmen when eight eastern European countries joined the EU in 2004, followed by Romania and Bulgaria this year.
But those restrictions are due to expire by 2011, and have not stopped Austrians from stealthily recruiting Czech nurses for their elderly relatives, Slovak cleaners and Polish builders.
"Future immigration will to a large extent come from EU member countries, and therefore be hard to contain, even if you wanted to," says Thomas Madreiter, the head of urban planning in Vienna, which commissioned the as-yet unpublished study.
To cope with the growth, Vienna will double spending on new housing - 535 million (365 million) last year - over the next few years, Mr Madreiter said. That may help counter a backlash from right-wing parties, which have already made inroads among the ruling Social Democrats' voters on an anti- immigration ticket.
"We had decades of stagnating and even falling population," says Mr Madreiter.
"Now Vienna is a city of immigration again."