Like Ronald Reagan before him, Barack Obama is using the image of the Berlin Wall to issue a call for change in international relations.
While the former president called on the leader of the Soviet Union to tear down the wall that divided Berlin, the would-be president called on Europeans and Americans to join forces to "defeat terror and dry up the well of extremism that supports it."
In apparent reference to issues such as fighting terrorism and global warming, Obama said that differences between "old allies on either side of the Atlantic cannot stand."
He added that walls between rich countries and poor countries, as well as between religions, races and ethnicities, also cannot be allowed to stand.
According to police estimates, the crowd topped more than 200,000 -- the largest of his campaign. Obama told the throng that he was speaking only as a citizen.