For a time Sens usurped the claim to be the oldest of the Gothic cathedrals. Its choir was started as Romanesque, but the walls rose slowly, and before a stone roof crowned the ambulatory the new system of building had conquered public opinion. The choir-aisle walls, intended to carry a groin vault, were rearranged to bear one with diagonals. On the outer wall the diagonals were caught on corbels placed above the capitals, and though such an arrangement shows maladroitness, the ribs themselves were made by no novice hand. Sens was a pioneer in the use of the broken rib to avoid the curving of diagonals: from each keystone, set precisely in the center of each section, branched the four ribs.
The walls of the procession path and an apsidal chapel opening on the transept's north arm, are the oldest parts of Sens Cathedral. It is true that they antedate the dedication of St. Denis, but not by a few Romanesque vestiges can Sens substantiate its claim to be the first built of Gothic cathedrals. In its main parts it belongs to the third quarter of the XII century. It was a distinct advance on Noyon and Senlis, because it eliminated the deep tribunes over the side aisles. One of the striking characteristics of Sens is the way that light floods it from the aisle windows, which are on a noble scale. Because the church was built during a tentative hour its deficiency lies in the height of the central nave. For right proportion, when flanked by such lofty aisles, the nave should have been made considerably higher.
Sens Cathedral was begun by Archbishop Henri-le-Sanglier (1122-43) to replace a church dedicated at the end of the X century. Such strides has mediæval archaeology taken in France during the last generations, it is hard to believe that serious students, during the Congrès Archéologique held at Sens in 1840, could have considered the present edifice to be the one dedicated before 1000.
Henri-le-Sanglier had been appointed by Louis VI to the see of Sens before he had received holy orders, and in the lax spiritual standards of the day, he saw no harm in living like the feudal lord he was by birth. He had not Thomas of Canterbury's unbending consistency. When his worldliness was censured by St. Bernard he changed his way of life, and ultimately proved himself a loyal and humane pastor.