Zakomara (Russian: Закомара) is a semicircular or keeled completion of a wall (curtain wall) in the Old Russian architecture,^[1] reproducing the adjacent to the inner cylindrical (convex, crossed) vault.

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False zakomar, which is not repeating the inner shapes of the vault, is called the kokoshnik. Kokoshniks were only made as exterior decorative elements. They were placed on the walls, vaults, as well as the shrinking tiers at the base of the tents and reels of chapters in church buildings.

From the twelfth to the seventeenth centuries, zakomars were a typical detail in the ancient Russian Orthodox church architecture. Quite often, a combination of zakomars and kokoshniks was used in the construction of many churches.

The roof in the zakomar covering was arranged directly on the vaults. Depending on the number of vaults, the facade of the church had the same amount of zakomars. By the seventeenth century, a significant number of Russian churches had the zakomar covering. But sophisticated curvilinear rooftop was not very practical—the snow and rain accumulated on it, causing leaks. By the end of the seventeenth century, the Baroque era came to the Russian architecture, making the zakomars and zakomar coverings a thing of the past. In the eighteenth and nineteenth centuries, zakomar coverings were replaced with four-pitched roofs in many churches. Because of the spread of the retrospective trends in the Russian Empire’s architecture, zakomars reappeared in the church buildings.

At the end of the twentieth century, the revival of the zakomar covering has occurred. It was due to the appearance of construction technology, which created rain and snow resistant zakomar coverings. Therefore, the new Uspensky Cathedral in Yaroslavl has the zakomar covering.

• Zakomars of the church of the Intercession on the Nerl
• Facades of Transfiguration Cathedral in Pereslavl-Zalessky, with zakomars
• Saviour Cathedral of the Andronikov Monastery, combination of zakomars and kokoshniks typical for Moscow style
• Trinity Cathedral of the Trinity Danilov Monastery in Pereslavl-Zalessky with a roof rebuilt as hipped one