*AP*The flame on Thursday was lit by Greek actor Katerina Lehou
The flame for the Olympic Games in Brazil has been lit in southern Greece.
An actor performing the role of high priestess lit the torch by using the sun's rays.
The torch will be taken by various runners on an international relay that will culminate at the opening ceremony in Rio de Janeiro on 5 August.
The ritual was established 80 years ago for the Berlin Games, based on a ceremony in Ancient Olympia where games were held for more than 1,000 years.
Actor Katerina Lehou, who lit the torch, offered a mock prayer to Apollo, the old Greek god of light and music, at Thursday's ceremony.
Wearing a long pleated robe, she knelt solemnly to the ground and lit the torch within a few seconds by using a concave mirror to catch the sunlight.
*Reuters*The flame was lit after a mock prayer was offered to Apollo, the old Greek god of light and music
She then delivered the flame to Greek world gymnastics champion Eleftherios Petrounias, the first runner in a torch relay that will conclude at the opening ceremony in Rio's Maracana Stadium.
Before that it will begin a six-day relay across Greece, passing through the town of Marathon - which which gave its name to the long distance race - as well as a camp for refugees and migrants in Athens, the International Olympic Committee has said.
The flame is due to arrive in Brazil on 3 May for a 100-day relay across the country, travelling through 500 cities and villages in every Brazilian state.
It will be carried by about 12,000 torch bearers.