Berliners have failed to back attempts to keep open the city's historic Tempelhof airport, according to early referendum results.
Just over 21% of Berlin's 2.4m voters opposed plans to close the airport, but 25% were needed for the non-binding vote to be considered valid.
The airport's backers had hoped a strong vote would persuade city leaders to change their minds.
The airport played a crucial role in the Berlin Airlift during the Cold War.
The airport, one of the world's biggest buildings, was built in 1923
Of those who voted, 60% were opposed to the closure while 40% supported it, but only 36% of the city's electorate turned out, leaving the no vote below the necessary threshold.
And Berlin's mayor had in any case said he would push ahead with the closure regardless of the result.
The BBC's Tristana Moore in Berlin says the results are a blow to members of the Save Tempelhof group, who had organised a slick advertising campaign over the past few weeks.
The airport has been threatened with closure for more than a decade.
The authorities want to close it in October to make way for a new international airport on the outskirts of the city, arguing that it has been running up heavy losses and is no longer viable.
But, our correspondent says, campaigners claim Tempelhof is the ideal inner-city airport, catering for business travellers and short-haul flights within Europe, as well as saying it is a symbol of the city's history.
A huge fleet of planes supplied West Berlin in 1948
Tempelhof is Germany's oldest commercial airport - and is claimed to be the world's third largest building, behind the Pentagon in the US, and Ceausescu's palace in Bucharest.
During the Cold War, from June 1948, Allied aircraft landed at Tempelhof, delivering thousands of tonnes of food and supplies to the residents of West Berlin, which had been cut off by the Soviet Union.
The crisis started on 24 June 1948, when Soviet forces in the eastern zone blocked Allied rail and road access to the western sectors of Berlin.
The Berlin Airlift was one of the biggest humanitarian air relief missions in history.