Plans are being drawn up for a European Union "state ceremony" to mark the death of Helmut Kohl, the former German chancellor, who died on Friday, aged 87.
Mattarella wrote to German President Frank-Walter Steinmeier saying "I have learned with deep sorrow of the passing of Helmut Kohl, a political personality of extraordinary significance in the recent history of Germany and the whole of Europe". "We mourn", Kohl's Christian Democratic Union party (CDU) tweeted with a picture of the former chancellor.
Born on April 3, 1930, in Ludwigshafen, a western industrial city on the Rhine, Kohl joined the Hitler Youth but missed service in the Nazi army.
"When a new spirit began to sweep through Eastern Europe in the 1980s, when freedom was won in Poland, when courageous people in Leipzig, East Berlin and elsewhere in East Germany staged a peaceful revolution, Helmut Kohl was the right person at the right time", said Merkel.
He went on to become the Minister-President of Rhineland-Palatinate from 1969 to 1976. As a 15-year-old, he was about to be pressed into service in a German anti-aircraft gun unit when World War II ended.
Former President Bill Clinton (R) hugs former German Chancellor Helmut Kohl (L) after awarding the Medal of Freedom award to Kohl in the East Room of the White House, Washington D.C., April 20, 1999.
"Kohl was the leader who united Germany with a determined and steady hand".
"He held fast to the dream and goal of a united Germany, even as others wavered", she said.
Juncker said that "without Helmut Kohl, the euro would not exist".
Still, the "blooming landscapes" that Kohl promised East German voters during reunification were slow to come after the collapse of its communist economy, and massive aid to the east pushed up German government debt. He was previously married to Hannelore Renner in 1960, who committed suicide due to an unbearable medical condition.