Clean Monday, also known as Pure Monday, Ash Monday, Monday of Lent or Green Monday, is the first day of Great Lent throughout Eastern Christianity and is a moveable feast, falling on the 7th Monday before Pascha. Revellers in Greece celebrate ‘Ash Monday’ by participating in a flour war to mark the end of the carnival season. (top left pic) A reveller celebrates Ash Monday to mark the end of the carnival season. (top right pic). Revellers celebrate Ash Monday by participating in a flour war. (bottom left pic). Revellers celebrate Ash Monday to mark the end of the carnival season. (bottom right pic)