To mark Epiphany, Sean Fletcher is in Durham for the UK's largest light festival. He joins tens of thousands of visitors who come to see the medieval city and towering cathedral transformed by light installations. Falling each year on 6 January, Epiphany is the twelfth day of Christmas and marks the end of the festive period. Sometimes known as Three Kings' Day, it is a time to remember the story of the wise men led by a star to Bethlehem to worship the infant Jesus. Sean meets professor of physics Tom McLeish to discover more about this part of the Christmas story and explores the great cathedral to learn more about its rich Christian history. Music: Brightest and Best - Church of St Cross, Winchester We Three Kings of Orient Are - St Mark's, Maida Vale O Lord of Every Shining Constellation - Christ Church, Port Sunlight It Came Upon the Midnight Clear - Romsey Abbey My Jesus, My Saviour - St Catherine's Church, Pontypridd Lux Aeterna - Pershore Abbey O Worship the King - Pershore Abbey Angel Voices Ever Singing - Romsey Abbey.