BERLIN (AFP) - Barack Obama Thursday told a staggering crowd of 200,000 people in Berlin that Americans and Europeans must tear down walls between estranged allies, races and faiths, in a soaring challenge to a new political generation. ... humanity must build "a world that stands as one," before the biggest crowd of his campaign. "The greatest danger of all is to allow new walls to divide us from one another," said Obama, who has scorched through US politics at lightning speed to challenge Republican John McCain for the White House in November's election. --snip-- The crowd was put at...