The belfry tower is a unique monument of 17th-century Kostroma fortress architecture. It was built as part of the monastery walls between 1642 and 1648 as a passage tower with holy gates. On a low square base with an arched passage oriented from west to east, an octagonal structure with a cornice of machicolations is placed. The facades are adorned with modest decor: pilasters at the corners of the square base and round loopholes framed under the machicolations. The upper part of the tower, which serves as the belfry, was added in 1865 and restored after a fire in 1887. From 1977 to 1980, the building was restored by KSNRPM. The addition, executed in the Russian style, includes an octagonal bell chamber with paired arches and a tent with decorative kokoshniks at the base, dormers, and a dome at the top. The decorations of the addition reflect the spirit of the 17th century and include flares, kokoshniks, and brick belts.