Begun in 1153, this cathedral was not opened until 1191. The changes made after the fire of 1504 (caused by lightning) have given the cathedral its present-day look. The magnificent spire (78m) inspired numerous bell towers of the Valois. The original polychromy of the impressive great doorway has been restored. The façade of the transept on the south side (16C) contrasts with the main façade (12C), highlighting the evolution of Gothic art. Inside, the nave and the chancel, narrow for their height, seem to soar above you; the tribunes are among the finest in France. Just twenty minutes from Mouy, lovely to visit on the market days of Tuesday and Friday.