Germany's autobahn was closed to cars and other automobiles on Sunday as it became the scene for a giant street festival in which around two million people took part, organizers said.
Cleared of traffic jams and engine exhaust for 31 hours, the 60-kilometre (40-mile) stretch of one of Europe's busiest motorways, between the western cities of Dortmund and Duisburg, became a stream of pedestrians and cyclists.
Thanks in part to warm sunny weather, the turnout was double what was expected as visitors passed by 20,000 picnic tables lined up end-to-end in what organisers dubbed a moveable feast of "everyday life and culture".
"The motto of the Still-Life event is 'The table is your stage'," event spokeswoman Katharina Jarzombek said.
"Anybody can showcase their band, their hobby, their club or their group of friends."
A police spokesman declined to provide an official estimate of the turnout.
Among the participants from the United States, Japan and across Europe was a club of "Star Wars" fans putting on a tribute to the science fiction blockbusters and a brass combo called Tuba Libre.
The event was a highlight in the Ruhr 2010 European Capital of Culture festivities, which has seen Germany's rust belt region transformed into a hotbed of the arts with hundreds of concerts, plays and exhibitions planned throughout the year.