Good Friday (29 April): The celebration date changes every year. The day commemorating Jesus Christ's crucifixion.
Holy Saturday (30 April): The celebration date changes every year. The last day of Holy Week and of Lent. At midnight the Resurrection of Christ is celebrated.
Easter Sunday (1 May): The celebration date changes every year. The most important Christian celebration, celebrating the Resurrection of Christ.
International Workers day (1 May): Dedicated to the Chicago workers riot in May 1886 demanding an 8-hour work day and better working conditions.
Easter Monday (2 May): The celebration date changes every year. The second day of Easter.
Anniversary of the Union of the Ionian Islands with Greece (May 21): Celebration of the union of Lefkada and the rest of the Ionian Islands with the independent Greek state which took place on May 21, 1864.
Dormition of Virgin Mary (15 August): One of the most important orthodox celebrations, celebrating the passing and burial of Virgin Mary, with glorious ceremonies in many parts of Greece.
"No" Day (28 October): On this day the Greeks celebrate dictator Ioannis Metaxas's refusal, on 28th October 1940, regarding Italian claims, leading to Greece taking part in WWII.
Christmas (25 December): One of the most glorious celebration of Christianity, celebrating the birth of Jesus Christ.