The leaders of France and Germany have marked the 50th anniversary of the Elysee Treaty, which sealed their reconciliation after World War II. French flags are flying beside those of Germany in Berlin.
President Francois Hollande told a joint session of their parliaments in Berlin that a generation had grown up knowing only peace and democracy.
But he warned that they faced "an economic and social crisis of unprecedented duration".
Chancellor Angela Merkel said the two states would work on deeper economic and fiscal integration.
The Elysee Treaty was signed by Charles de Gaulle of France and Konrad Adenauer of Germany on 22 January 1963.
''I'm very happy with what France and Germany have been able to accomplish to get the eurozone out of its crisis,'' said Mr Hollande on Wednesday. "If you look at the results, it's clear we're on the same wavelength."
However, the BBC reports the two countries remain at odds on several issues, including how to deal with the eurozone crisis.
President Hollande - who is pushing for fresh spending to bolster growth - believes that the Germans are wrong to place such emphasis on austerity and cutting deficits.