The cathedral of Notre-Dame of Laon is one of the most important examples of the Gothic architecture of the 12th and 13th centuries . It has been compared to the cathedrals of Saint - Ã tienne of Sens and Notre Dame of Paris . Laon Cathedral ( CathÃ drale 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 .