Located at the center of the presbytery, crowning the masonry altar, rises the ciborium. It is an object of extraordinary preciousness and fragility, as it is entirely made of stucco over a core of river reeds. The upper structure rests on four reused marble shafts taken from a building of the Roman period, probably portions of an architrave roughly shaped to make them cylindrical. One of them, the rear right shaft, still preserves part of the inscription that once ran along the entire frieze; the abbreviated name Titus Iunius can be read. Resting on these shafts are four stucco capitals, decorated with five large leaves on each side. Above the capitals rise large arches, with archivolts in relief with respect to the four faces and the roof. The faces are adorned with a band forming various net-like interlacings across the entire surface, with a continuous and uniform design, while the archivolts display an interwoven pattern of multiple knots. The slabs are still joined by wooden pegs, in some places still clearly visible. Looking inside, beneath an area where the stucco has fallen away, it is possible to see the core made of river reeds.
The question of its dating remains open: some scholars place it in the 10th century, while others move the date of execution forward by a century, based on stylistic comparisons between these capitals and those of the abbey church of Saint-Benoît-sur-Loire in the Berry region. It was created by craftsmen familiar with the most up-to-date artistic trends of the period in the transalpine regions and, precisely because of its high artistic value, it was reinstalled in the 12th-century Romanesque church.
Now let us turn our gaze toward the back wall, on the right side of the presbytery, where one can admire the elegant armarium, that is, a small shrine in the form of a little temple. It is composed of two twisted columns with simplified Corinthian capitals supporting a double-pitched roof. On the front is a coat of arms with six flames. At the base, reused cornices can be admired. It dates to the 14th century, and the Eucharist was kept inside it. On the opposite side, instead, one can admire an elegant altar table made with reused materials. Among these, a small pilaster decorated with interlaced bands can be recognized, which once supported a Carolingian-period choir screen.
