The exhibition route, entitled “Nel Cuore della Chiesa” ('In the Heart of the Church') constitutes of the results of the archaeological search carried out on the occasion of the architectural restoration and post-earthquake reconstruction of the plebanale building, and has been conceived in such a manner as to provide the visitor with basic knowledge regarding the history of this sacred building, presented in chronological order.
The surviving remains are presented together with the mortal remains of the 'scheletro' (skeleton), the last medieval “occupier” of the sepulchre. It is curious to discover, today, how in a different time period, a tower was to be built just on top of the relict of the “privileged” late Roman period tomb.
During the course of the twelfth century, the church was expanded and furnished, in the east, with three 'absidi semicircolari' (semicircular apses). It is probable that this was the work of the Benedictine fathers. Approximately 28,000 fragments of frescoed plaster have been found in concentrations along the south perimeter wall and to the east of the central apse of the three apse church. They are what remains of its wall decoration which was created during different ages.
At the end of the fifteenth century, the three apse church was destroyed and substituted with a new building which had 'tre three' (three naves) and a polygonal apse, with a solid bell tower. The last radical transformation happened in 1777.