Surrounded by several dozen survivors of the siege, President Vladimir Putin visited the famed Piskaryovskoe Memorial Cemetery, the main memorial to the victims of the siege of Leningrad, the Soviet-era name of Saint Petersburg.
Putin, who hails from the city, has said his elder brother died during the blockade.
The president laid flowers at a memorial on the banks of the Neva River marking the site of one of the most important battles during the siege in which his father took part.
The 872-day siege by Nazi forces between September 1941 and January 1943 is seared into the national consciousness as one of the darkest moments in Russian history. The blockade of the former imperial capital claimed the lives of more than a million people, according to historians.
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Most of them died of hunger, their bodies littering the streets for days as survivors were too weak to bury the deceased.
Earlier today, some 1,500 people took part in a military parade showcasing Soviet-era war-time T-34 tanks as well as modern Iskander ballistic missiles.
"When I look at the chronicles and the pictures I can barely hold back tears," said Natalia Zvereva, 60, who brought her grandchild to see the exhibition. "It was such an awful time."
Sergei Stepanenko, 45, added: "My grandmother survived the blockade. She could not talk about it. It was too horrible.