[Illustration: No. 43. Romanesque Tower, Thaon, Normandy.]
At the end of the nave, projecting transepts separated it from the chancel (which is generally raised in level), continuing the line of nave, the whole taking the shape of the Latin cross in contrast to the Byzantine plan; the chancel end facing East, the nave West, and the transepts respectively North and South.
A feature of this period is the Apse, a semi-circular extension of the choir or chancel; when the side aisles were extended to the latter they formed what is known as an ambulatory, or passage way, round the choir, within which was the altar, and the stalls for monks and clergy.
The Narthex or atrium, of the basilicas, utilised by the early Christians for their public worship (to which were admitted those outside the community) was abandoned, its place being taken by the West entrance or porch, enclosed between two towers.
[Illustration: No. 44. Romanesque plan of Cathedral, Worms.]
The upper walls of the nave were carried on arches supported by columns, which constituted the division of the side aisles; these latter being formed by vaultings from the nave columns to the outer walls, the vaulting being roofed over.
The upper part of the nave was pierced by windows, small and comparatively narrow, with semi-circular heads forming the Clerestory. Similar windows in some instances occur in the aisles, the jambs of these windows being bevelled both inside and out for the freer admission of light.
The nave was roofed in with timber, but as the result of frequent destruction by fire, the roof was eventually vaulted; in early examples by the barrel or tunnel vault, but later this developed into cross-vaulting, which was also introduced into the side aisles.
[Illustration: No. 45. Romanesque, bay of interior, Worms Cathedral.]
[Illustration: No. 47. Romanesque Church interior with Triforium.]
[Illustration: No. 46. Romanesque Window, St. Alban’s Abbey.]
In the early churches of this period the walls of the nave were unbroken except for the upper windows. With the development of vaulting, the space above the aisle vaults and the covering roof was used as a gallery known as the Triforium. This was not lighted from without, and was a distinguishing characteristic of the Romanesque and early Gothic styles.