There are no walls; the cathedral may be said to consist of windows, rose-windows, and “stone lace-work.”
The strength of the whole structure depends upon a series of pillars and arches which, according to the principles of Gothic construction, ensure equilibrium, by dividing the pressures and opposing conflicting stresses.
The triforium has lost that importance which it had in the early Gothic edifices. Here it is a narrow gallery running right round the church. In the nave it comprises, at each bay, two wide arches divided by two slender columns.
The windows are 52 feet high and of the same width as the arcades on the ground floor.
The original stained glass no longer exists.
According to the canons of Gothic art, all ornamental carving must be inspired by Nature.
The typical ornamentation for capitals is the crocket, intermingled here and there with other kinds of foliage.
The belt of foliage below the triforium represents plants grown exclusively in Picardy, and is very finely executed.
At the entrance to the nave, with its back to the first pillar on the right, is the early 16th century tomb of Canon Pierre Burry (1 on plan). It is a fine, expressive statue of the canon kneeling, presented by his Patron Saint, St. Peter, to an “Ecce Homo” of little note.