Laon Cathedral (Cathédrale Notre-Dame de Laon) is one of the most important examples of the Gothic architecture of the 12th and 13th centuries, earlier than the cathedrals of Sens and Notre Dame of Paris and ranking with them in importance. It is located in Laon, Picardy, France, and is the seat of the Bishop of Laon. It has been listed among the Monuments Historiques since 1840.