Three statesmen who oversaw the crumbling of the Berlin Wall 20 years ago gathered Saturday in Germany's capital.

Former U.S. president George H.W. Bush; the last Soviet leader, Mikhail Gorbachev; and former German chancellor Helmut Kohl were honoured at a ceremony in Berlin marking the end to the concrete barrier that once snaked across the city.

Helmut Kohl, the first chancellor of reunified Germany, had a thorny relationship with the Soviet Union, a ceremony in which he partook Saturday heard. ((Associated Press/Herbert Knosowski))

Kohl, 79, who went on to become the first chancellor of a reunited Germany, appeared the most visibly moved by the moment, recalling the heady days that led up to the Nov. 9, 1989, collapse of the wall and Washington's and Moscow's willingness to let it fall.

"We achieved reunification together, with peace and freedom and with the support of our neighbours," Kohl recalled.

"We don't have many reasons in our history to be proud," Kohl said. "But those years when I was chancellor, ... I have every reason to be proud. I have nothing better, nothing to be more proud of than German reunification."

In his speech, Bush, 85, said the wall's collapse was possible because of people "who so long had to strive for their God-given rights."

Gorbachev, 78, recalled the efforts of the many political leaders who fought throughout the decades of the Cold War for reconciliation between Russia, Germany and the West in small steps and tiny concessions.

"How difficult it all was!" he said, noting that even the initial working relationship between him and Kohl was thorny.

Gorbachev referred to his campaign in the 1980s of promoting economic restructuring and called on the U.S. to carry out its own set of reforms.

"America also needs a perestroika," Gorbachev said, noting the push for change with the election of U.S. President Barack Obama. "A lot will now depend on America.... Leadership will have to be proven."

For 28 years, the divisive landmark split the German capital between parts held by East and West Germany and came to symbolize the barrier separating European communist countries from Western capitalist democracies.

East Germans were not allowed to leave their country without permission. It's estimated several hundred people were killed trying to escape to the West.