The Katskhi Monastery of Nativity of the Savior was built at the behest of the Baguashi family in the period of 988–1014. The church building is noted for a hexagonal design and rich ornamentation. Closed down by the Soviet government in 1924, the monastery was revived in 1990 and is now operated by the Eparchy of Sachkhere and Chiatura of the Georgian Orthodox Church.
The Katskhi monastery is a octagonal building of more complex design than other similar polygonal Georgian monuments. The exterior of the church features three gradually narrowing cylindrical levels formed by the faceted gallery, the main body of the church, and the drum of the dome.
The six apses are inscribed into the outer polyhedron and surrounded by an ambulatory from all sides. A single spacious interior compartment around the subdome bay includes radially oriented semi-circular apses. One of these, the altar apse, projects outward prominently due to its large bema. The drum of the dome is also faceted. Each facet of the main body of the church as well as that of the dome and gallery terminate in a pediment with three lines of polygonal cornices.
The building was richly ornated, but the decoration of two upper tiers was lost in the process of the 1854 restoration. Of note is a large composition in relief at the southern vestibule of the gallery, the Exaltation of the Holy Cross, featuring a cross supported by four angels.
The church is surrounded by a pentagonal wall, which contains a free-standing bell tower in its eastern corner. These structures are later additions, probably from the 17th or 18th century.
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The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.