Remembering the Armenians killed by Ottoman Turks in 1915.
World leaders, including the presidents of Russia, France and Serbia, have gathered in the Armenian capital for the 100th anniversary of the massacres of up to 1.5 million people.
It is called a genocide by about two dozen countries around the world, and on Thursday the German President used the word, the first time it has been used officially in Berlin.
Joachim Gauck also admitted that Germany bore some responsibility in the deaths as an ally of the Ottoman Empire.
Pope Francis also recently referred to the deaths as genocide.
Turkey angrily rejects use of the term, insisting there was no organised campaign to wipe out Armenians, saying there were high death tolls on both sides.
But the Armenian President today called on more countries to recognise the killings as genocide.
The presidents of Russia and France also addressed the dignitaries gathered. They both referred to the killings as genocide and spoke about the need to learn from the past and ensure similar tragedies are not repeated in the future.