The Nativity Cathedral, built on the territory of the fortress, was the central element of its construction until the early 19th century. Other buildings were located around it along the perimeter of the fortified citadel. The cathedral was erected on the site of a wooden church of the Life-Giving Source and is one of the oldest monuments of the city that has survived to this day.

Together with the Spasskaya Tower from the late 17th century and the Kazan Cathedral, built between 1866 and 1872, it forms an expressive architectural ensemble on the high left bank of the Syzran River. Built with funds from merchant A.V. Kandalayev in the Naryshkin Baroque style, the Nativity Cathedral served as a model of style for local cult architecture until the early 19th century. This is confirmed by the appearance of later parish churches, which were built of stone instead of wood in the second half of the 18th century.

The plan of the Nativity Cathedral is based on a three-part composition: the cathedral itself with a three-apsidal altar, and the refectory, located along the longitudinal axis. The central part of the cathedral is designed according to the popular scheme of the time, "an octagon on a square." The base of the plastered brick building is adorned with two semi-vaults. The refectory has a gable roof with a pediment at the end. The octagon, pierced with small rectangular windows, is topped with a slightly flattened dome. The structure is completed with a faceted onion dome on an octagonal neck, decorated with narrow rectangular niches. A bell tower was not built at the cathedral, as the bells were located on the Spasskaya Tower.

In the interior, the main space and altar are connected by three arched openings. The temple is covered with a closed eight-section vault on trompes, while the apse and refectory have barrel vaults with arches above the windows. The corners of the square, the refectory, and the joints of the apses are emphasized externally with pilasters decorated with strips. The main volumes are surrounded by cornices with rows of small brackets. Rectangular windows and door openings are framed with architraves with arched lintels, except for the main entrance with a semicircular finish and an archivolt. There are a total of 17 window openings with small square divisions: four in the refectory, three in the central square, four in the octagon, and three in the altar part. The asymmetrical arrangement of windows in the square recalls the traditions of 17th-century architecture. Thus, the Nativity Cathedral is a combination of ancient Russian traditions and the new Baroque style.