UPDATED 6.34PM: Thousands of Greeks have taken to the streets to celebrate the victory of the leftist Syriza party, dancing and singing in a plaza in central Athens known as the Square of Tears for its tragic past.

"Greeks have shed tears of sorrow in this very square, and now they are finally shedding tears of happiness and hope for a new tomorrow for the country," 44-year-old taxi driver Giorgos Balabanis said late on Sunday.

In modern Greek history, the square has been connected with the 1942 rounding up of Greece's Jewish population by occupying German forces.

More recently it has been the scene of violent anti-austerity demonstrations and riots over the last five years, which resulted in the deaths of three employees in a torched bank nearby.

Almost overnight, the winds of change made their mark on the square as folk and revolutionary songs blasted from loud speakers to a crowd of happy revellers.

"People are finally celebrating and feeling happy for the hope that is coming and the responsibility for what we need to do," 50-year-old school teacher Sofia Korsavidou said.

"We have had enough of endless austerity, the unemployment, the suicides and the misery, which has been brought upon the Greek people.

"This is a new era not only for Greece but for all of Europe - the people, not the banks, have the power."

Elsewhere around Greece the mood was similarly joyous. People could be seen Greek dancing in the streets in the Cretan capital of Irakeio while villagers in Tsipras's father's town, Epirus, could be seen still drinking and dancing early Monday.