Final answer:
In the context of church architecture, the main portal bifurcates at the entrance, with the trumeau serving as the central dividing element. This division is often decorated with religious sculptures symbolizing guardianship and storytelling of sacred narratives.
Step-by-step explanation:
The main portal typically bifurcates or divides in a church facade where the entrance is parted by a central column or trumeau. This bifurcation occurs at the entrance of many Romanesque and Gothic churches, often richly decorated with sculptures and carvings of religious significance. As an example, in the case of Ste. Pierre, the portal is bisected vertically by the trumeau, which itself is adorned on its sides with symbolic sculptures. These may include figures from both the Old and New Testament, such as prophets and saints, serving as spiritual guardians of the sacred space within the church.
Befitting its role, the portal and its dividing trumeau are intricately carved, illustrating the artistic and religious narrative meant to be conveyed to the faithful entering the church. As such, the trumeau serves both a structural and decorative purpose, echoing the broader context in which art and architecture merge in the service of spirituality and storytelling within ecclesiastical settings.