In western culture Friday the 13th is considered an unlucky day. It occurs when the 13th day of the month falls on a Friday, according to the Gregorian calendar. The superstition arose during the middle ages and is rooted in the story of the last supper of Jesus and his crucifixion, when he was with 13 disciples in the Upper room on the 13th of Nisan Maundy Thursday, the night before his death on Good Friday. In Greek folklore it is not Friday, but Tuesday the 13th that is considered unlucky. The Fall of Constantinople during the fourth Crusade occurred on Tuesday, April 13th, 1204, while Constantinople was finally conquered by the Ottomans on Tuesday, May 29, 1453. The word Tuesday in Greek is ‘Triti’, which literally means ‘third’, another point that adds weight to the unlucky day, as bad luck is believed to come in threes.