In the first half of the 19th century, the main cathedral square of the city was built up with buildings in the classical style, most of which have survived to this day, forming a unified architectural ensemble. The central element of this ensemble is the Cathedral of the Assumption of the Mother of God, built between 1805 and 1820 according to the design of architect I. Manfrini.

The Assumption Cathedral, a significant architectural structure in the classical style, still remains a dominant feature of the old part of the city. Its central part, a square base with a semicircular apse, serves as the foundation for a wide drum topped with a flat dome. On the western side, a small refectory and a three-tiered bell tower adjoin the cathedral. The northern and southern facades of the square, as well as the western facade of the lower tier of the bell tower, are adorned with porticos of the Ionic order with triangular pediments. The architect added four high semi-cylindrical volumes adjacent to the western and eastern walls of the square so that the side domes appeared proportionate to the central dome. The upper part of the building is lightened by numerous through and false windows of various shapes. An Italian window is located on the central drum, and on the walls of the refectory, a triple window is complemented by a thermal window in the upper tier. Above the northern and southern portals, on the apse and side drums, there are large round windows, while rectangular windows are placed in niches with semicircular tops. The bell tower, visually balancing the enormous apse of the temple, now looks somewhat heavy due to later reconstructions and losses. Originally, it was more elegant. The Assumption Cathedral has also reached us with losses: the decorative domes above the domes and the through windows in the drums of the domes have disappeared, making it visually heavier. Previously, the facades were enlivened by yellow-white coloring, and the tympana of the pediments contained pictorial compositions on religious themes.

In the interior of the temple, frescoes created in the 1830s by an artel under the guidance of T.A. Medvedev, known in the Upper Volga region, have been preserved. The masters of this artel painted the Spaso-Preobrazhensky Cathedral in Uglich and the Resurrection Cathedral in Bolshie Saly. To create the effect of sumptuous decoration at minimal cost, the grisaille technique was used, imitating columns, cornices, and stucco. Compositions on themes from the Holy Scriptures are executed in reddish-brown tones and framed in ornate frames. In the pendentives under the central dome, the evangelists are depicted, in the altar, the New Testament Trinity, and on the southern wall, an inscription about the time of the temple's construction. The walls and ceiling of the refectory feature Old Testament scenes, such as "Moses strikes water from the rock with a staff," "The Bronze Serpent," and "Moses presents the tablets of commandments to the people."