On the north side of the bell tower, there is a small church dedicated to the Nativity of Christ. It was likely built simultaneously with the bell tower on the site of a previous wooden church with the same dedication. This small pillarless building features a sub-church and an elongated apse. A distinctive feature of the church is the wide narthex, which serves as an entrance to both the Nativity church and the church under the bells. The simplicity and rationality of the architecture suggest, as noted by V.A. Yadryshnikov in his work "Architecture of Old Russia in the 11th to early 20th centuries," that the stone church replicates the composition of the wooden church, likely a predecessor from 1620. The researcher adds that similar small cell churches were common, but their stone copies are rarely found in the 16th-17th centuries. The sub-church was originally not intended for church purposes and was used for various functions: it housed a locksmith's workshop, and from 1763, it was rented out as a storage for state wine.

In the early 19th century, according to monastery documents, there was a bakery with a pantry here. From 1835, this place housed the church of Cosmas and Damian, the altar of which was moved from a closed church of the attached monastery. It existed until 1892, when the Nativity church was transferred to the spiritual school.