In the donation act of Ugo di Gerberto from 1093, however, the church is dedicated to the Mother of God (Deigenetricis) and Saint Pellegrino, suggesting a name change, with the name Maria then appearing in the inscription on the ambo and the altar.

The single-lancet window has a round arch and is framed by a raised border hosting four corbels with lion figures.

The central apse is divided by two pilasters into three bays, each with a narrow window with splayed openings, and is decorated at the top with nine small arches.

The interior of the church features three naves separated by twelve columns, all different from one another, presumably made with materials recovered from the nearby Peltuinum, supporting round arches.

On the left side of the central nave, next to the fourth column, is the ambo from 1180, created by Abbot Giovanni.

The friezes support rectangular balconies, with the two lateral ones divided by a pillar into two sections, each containing a sculpted flower.