Tens of thousands thronged the route of the Berlin Wall on Monday for emotional celebrations to mark 20 years since its fall, but Chancellor Angela Merkel said Germany still bears the scars of division.
World leaders joined huge crowds recalling the defining moment of the end of communist rule in Europe, when the embattled East German state finally opened the despised concrete border on November 9, 1989.
Merkel, who grew up in the communist state, attended a "very moving" memorial service at a church where pro-democracy rallies were held in the weeks before the end of the communist regime.
"German unity is still incomplete," Merkel told ARD public television, noting how east Germany still lagged behind the west in economic growth, with joblessness nearly twice as high.
"We must tackle this problem if we want to achieve equal quality of life."
The chancellor gave her warning before the main ceremonies at the historic Brandenburg Gate with British Prime Minister Gordon Brown, presidents Nicolas Sarkozy of France and Dmitry Medvedev of Russia and US Secretary of State Hillary Clinton.
Former Soviet leader Mikhail Gorbachev, ex-Polish president Lech Walesa and dissidents who helped end European communism will also be on hand at the former "death strip" where border guards once had shoot-to-kill orders.