The Church of Alexander of Svir is located in the center of the village of Kosmozero and is its architectural dominant. It was built in 1769 with funds from the St. Petersburg merchant F. Popov. Initially, the church served as a winter temple and was part of an ensemble that also included the summer Assumption Church from 1720 and a bell tower added in the 1830s. These buildings were destroyed by fire in 1942.

The church is designed as a tent-like structure "octagon on a square". The walls of the building are log, with logs on the square and octagon. To the east of the square is a small five-walled altar with a five-pitched roof, topped with a barrel and crest. To the west are wider refectory and porch of the main entrance, covered with gable roofs at different levels. The roofing is made of nail-free planking. Entrance to the church is through open platforms on the south and north sides. The corners of the square are adorned with shelves as they transition to the octagon. The octagon has two tiers of the pediment belt, the lower of which is unfinished. The tent roof is made of smooth-planed planking in three tiers and is decorated with city-style cuts on the skirts. The tent is topped with a dome with a cross, covered with city-style shingles. The decor features "red" planking with truncated peak endings, carved cornice boards on brackets, and carved gables.

The church is a historical and architectural value, preserving the volumetric-planning structure of an 18th-century cult building, belonging to the Prionezhsky type of tent churches.