German Chancellor Angela Merkel will attend a ceremony in Berlin later this weekend marking the 50th anniversary of the building of the Berlin Wall.
For 28 years the wall stood as one of the most potent symbols of the Cold War, when the communist East closed its border, dividing the city in two.
Berlin Mayor Klaus Wowereit told a ceremony on Bernauer Street: "The Wall is history but we must not forget it."
The city will observe a minute of silence on Saturday night in memory of those who died trying to escape.
Earlier, Mr Wulff told Die Welt newspaper that the modern Germany could take pride in "East Germans' irrepressible desire for freedom and West Germans' solidarity with them".
Mrs Merkel, who was raised in the East, is attending the inauguration of a memorial and museum on Bernauer Strasse, which was divided by the Wall.