The aim of this paper is to study the liturgical arrangements realized in the transition space between the choir and the nave of the church, in order to obtain a better understanding of the link between the cathedral and the other monuments of the cult, in particular the baptisteries. The presented data are related to the one published on other sites: the cathedrals of Aosta, Tournai, Cologne, and Trier, and other buildings in western Europe. In the southern cathedral of Geneva, we observe, with a certain precocity, the emergence of a solea and an ambo, as in Aosta (half a century earlier), in Grado and Boppard during the same period, and in Tournai a little later. During the 6th century, this type of architectural element spreads throughout western Europe, and is in competition (or in complementarity) with more opened arrangements connecting the cathedral to the baptistery, as it is the case in the northern cathedral of Aosta, recently modified. During the 7th-8th centuries, the situation became more complex in Geneva, when, on the east of the baptistery, a third church was constructed, whose liturgical arrangements were those of a martyrial church. In the Carolingian period, this building was considerably enlarged on the western side (at exactly the same place where the baptistery was disappearing) and provided with arrangements similar to those of the cathedral of Cologne at the same time. This shows that it was now used as a cathedral, at the detriment of the two ancient churches that disappeared soon after. These constructions can be seen in relation with the application of the Carolingian liturgical reform, which was inspired by the image of Rome, as it can be seen in the Ordo Romanus IV, written in the Frankish kingdom.