The cathedral of Notre-Dame at Senlis dates from the third quarter of the 12th century, a period when the royal city of Senlis enjoyed "a golden age." Considerably altered in the 13th and 16th centuries, the fairly small cathedral is less well known than some of the other Gothic cathedrals. Although lacking the harmonious homogeneity of Noyon or Laon, its contemporaries, or the vast scale of Amiens, Senlis Cathedral is nevertheless an important building containing examples of all styles of Gothic architecture. In addition, recent cleaning has highlighted its decoration and it houses a rich collection of furnishings, spanning all periods of history of art. With its contemporary works of art, stained-glass windows and high altar, the cathedral is also a living monument.