The Cathedral of the Nativity of the Virgin Mary is the main structure of the Antoniev Monastery. It has survived to this day with changes and reconstructions carried out by L.M. Shulyak and D.M. Fedorov. The narrow windows with semi-circular tops were replaced with wide ones, and a tent-shaped iron roof appeared above the vaults. The domes acquired the bulbous shape characteristic of a later period. The galleries of the porch surrounding the cathedral were added later, and the ancient choirs have been lost. An interesting feature of the building's composition is the asymmetrical arrangement of the three domes, one of which crowns a round tower that protrudes from the main volume. This tower houses a staircase leading to the modern choirs of the cathedral.

In 1975, G.M. Shtendler and V.M. Kovaleva conducted additional research, which showed that the cathedral was originally a single-domed, four-pillar, three-apse cross-domed church. The modern western pillars are remnants of the wall. Fragments of frescoes have been preserved in the altar, among which is a figure with the inscription "Peter" above its head. It is assumed that this is a portrait of the master Peter, the builder of the cathedral. For the first time in ancient Rus, a departure from the canon of the three-nave six-pillar building was made here, where the supporting pillars always had a cross-section. The pilasters corresponding to the outermost pillars on the western side are absent, and on the northern and southern walls, they were later cut down.