**TRANSEPT. - I. Archaeological.**
The term *transetto* (transept) refers to that architectural feature placed transversely between the naves that extend longitudinally and the terminating part of the church. Etymologically, the word (from *transpetta*) means "beyond the enclosure" that originally divided the naves from the choir.
The origin of the transept is a matter of dispute among scholars, who, with few exceptions, have confined their studies to the broader problem of the pre-Christian basilica. Until recently, two entirely conflicting theories, each with substantial variations, dominated the field: the first advocated the derivation of the transept from particular architectural structures of Roman buildings (Dehio, Krauss, Glück, etc.); the other denied any pre-existing model and attributed its creation to Christian artists, whether for symbolic reasons (e.g., Christ, as in the plan of a cross), or for liturgical needs (Grisar and initially Wulff, Klauser, Schneider, etc.). Recently, G. P. Kirsch, together with Giovannoni, advanced a new theory, according to which the transept is an exceptional element in the Paleo-Christian basilica (in the East and West, as well as in North Africa, its presence is very rare in churches from the 4th to the 7th centuries); its genesis was influenced by various elements and factors to be sought in each locality, not excluding the inevitable influences between regions. Once the origins are established, only a comparative examination of groups of monuments, taking into account the individual contribution of the builder-architect, can allow for a general concept supported by positive factual data.
The insertion of the transept into the development of the naves created new static problems in the members of the crossing and new structural schemes. Architects sometimes preferred to limit the transept within the walls of the side aisles, at other times to extend it outward, thus creating that typical Latin cross which would become a characteristic of Romanesque churches. A special form of transverse nave is found instead in buildings with a central plan, those with a Greek cross, and other less frequent forms scattered in the East and West.
The transept was divided in various ways from the naves. First, an essential feature arose from structural needs: the triumphal arch, which served to support the intersection of the central nave with the transept. Later, the transept was divided into two parts by a wall, which, in the Romanesque period, often became a screen wall, while in the Gothic period it was replaced by a rood screen. The latter, in turn, was destined to disappear in the Renaissance, when the churches were brought back to the simple Latin cross plan. The arms of the transept then generally became rectangular; in Santo Spirito in Florence, Brunelleschi continued in the transept the same subdivision into bays as in the nave and side aisles, not only to ensure uniformity in the roofing system but also to express the structural coherence and spatial unity of the entire architectural organism. In the following century, Palladio returned to the apsed transept to harmoniously balance, with the transverse expansion of internal space, the upward thrust of the dome. In later churches, however, the model of the Gesù prevails, where a similar effect, albeit with less harmony, is achieved by rectangular arms contained within the alignment of the chapels.
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