On funeral wreaths and elegiac couplets, a name + 千古 means 'may X be remembered forever', much like 'rest in peace' on a gravestone.
usage
Set phrases: 名垂千古 'to be remembered for all time', 千古绝唱 'a masterpiece for the ages', and the saying 一失足成千古恨 'one false step brings a lifetime of regret'.