Postcard from... Berlin

He is best known for helping to create reunified Berlin's somewhat overblown reputation as Europe's "cool" city. Not long into his career, Klaus Wowereit, the German capital's party-mad and proudly gay Social Democrat mayor, described his city as "poor but sexy".

The phrase conjured up visions of a lost Bohemian way of life – a notion which continues to attract increasing numbers of visitors to the once-divided Cold War capital.

But the party now looks as if it may soon be over for "Wowi", as Mr Wowereit is dubbed by his friends. Eleven years ago the Berlin mayor set himself up as the champion of "Willy Brandt International", a new mega-airport that was to be built on the south-western fringes of the city, commensurate with Berlin's hoped-for role as central Europe's number one metropolis.

The new airport, initially priced at €2bn, was meant to open last June. But bungled planning and a host of defects meant the opening date had to be put back to October 2013.

This week it emerged that the airport's structural shortcomings are so "appalling", as one inspector put it, that the opening has had to be postponed until late 2014 at the earliest.

The costs have already doubled to around €4bn and the new delay is expected to add a further €1bn to the bill.

Mr Wowereit has responded by resigning as head of the airport supervisory body. But there seems little doubt that his days as mayor are also numbered. Being "poor and sexy" is one thing but Berliners are unlikely to think that having a billion added to their tax bill is "cool".