The building of the nave is usually attributed to Bishop Eborard (1121-45), but some eminent archaeologists believe that the whole cathedral, nave and all, was built by Herbert, 1091-1119, the first bishop and founder. We believe there is no documentary evidence against this theory. The Registrum Primum says: "Moreover, the same Herbert completed the church of Norwich in his own time, as I have learned from the account of old people, but have not found in writing, as far as the altar of the holy cross, which is now called the altar of S. William."

The billet enrichment on the main arches, and the chevron or zig-zag on those of the triforium, have been looked upon as indicating that this part of the building—the five western bays of nave—is later than the presbytery, the arches there lacking this ornament. But as these are quite the earliest forms of ornament used by the Norman builders, their occurrence here at Norwich cannot prove much. It is better perhaps to reserve judgment, and be content with merely stating the facts and the more generally accredited theories as to the age of the western part of the nave.

The subsidiary circular columns in the fifth bay of the nave from the west end should be noticed. A small enriched shaft in the clerestory of the north transept is here illustrated. This very beautiful style of treatment was common to the Norman builder, with the Romanesque, and the Romans before them.

The Choir Screen crosses the nave between the subsidiary piers to the sixth bay. Of the original work erected by Bishop Lyhart, 1446-72, the sub-structure of the present screen is the only portion remaining. Traces of two altars, one on either side of the doorway, can still be seen; these were originally dedicated to St. William of Norwich and St. Mary. These altars were enclosed in chapels formed by screens coming forward to the extent of half the bay, and stopped against the main nave piers on either side—the double vaulting shafts on the face of which are stopped by corbels, carved as heads, at about the height that the chapels would have reached. They were vaulted over, and above came the rood loft and organ. The rood loft was damaged by the Puritans, and probably removed after the Restoration. Dean Crofts, in 1660, set up a new organ.

In Britton's "Norwich," 1816, the upper stage of the choir screen is shown divided into square panels, occurring vertically over the lower stage; the screens to the chapels before referred to having been destroyed. In 1833 Salvin remodelled the choir, and turned his attention to the choir screen: the organ was placed in its present position, and cased with the frame of that instrument which Dean Crofts had set up in 1660; and the overhanging vault to the screen was added.

The Nave Vault (height 72 feet), which was added by Bishop Lyhart, 1446-72, took the place of the original Norman wooden roof destroyed by fire in 1463. This earlier Norman roof was most probably like that now existing at Peterborough, and was no doubt profusely decorated with colour. The vault is of Perpendicular design, and known as lierne; such vaults may be distinguished by the fact that between the main ribs, springing from the vaulting shafts, are placed cross ribs forming a pattern, as it were, and bracing the main ribs, but not in any great measure structural. This vault at Norwich may be taken as typical of the last legitimate development of the stone roof; it was the precursor of the later fan vaulting, such as we find in Henry VII.'s chapel at Westminster, where legitimate construction was replaced by ostentatious ingenuity and the accumulation of needless ornament and detail.

The carved bosses here at Norwich, occurring at the intersection of the ribs, are worth careful study. Those who care to go into the matter in the fullest detail should consult Dean Goulburn's book published in 1876, which not only gives an admirable history of the fabric and the See, but enters fully into the detail and symbolic meaning of each of the 328 bosses.

In this list, compiled from that volume, mention is made only of those bosses on the main longitudinal rib of the vault; it is hoped that this method will enable the visitor to readily enter into the meaning of any group of bosses, by providing a keynote to the whole. The subjects are taken from Bible history, and each epoch is usually grouped around some central incident figured on the main longitudinal ribs. In each bay No. 4 is the large central boss.