and A.V. Argun2. 1
Don State Technical University, 1 Gagarin square, Rostov-on-Don, 344000, Russia. 2
New Afon national historical and cultural reserve «Anacopia», 8 Eshba str., New Afon, 384840, Abkhazia.
Abstract. In the article the conceptual issues of the restorations and the architecture features of the gate node of the second line of the defense of Anakopia the capital of the early medieval of the Abkhazian Kingdom are considered. The round tower near the gate is unique by the nature of its arches. It was determined by the research that the tower was not built on a model but by the individual order. The analogues of the tower and its construction techniques were detected on the former territory of Byzantine empire – in Turkey, Greece, Armenia. The dates of the construction periods were specified from VI till XI c. Based on the results of the digital researches the features of the architecture of the monument in different periods were authentically restored.
The historical information about the territory of Abkhazia where is Anakopia found the reflection in the works of ancient authors . The mention of this fortress with its three thousandth garrison by the chronicle of Georgia when describing the Arab invasion at tests about the same, that the fortress of Anakopia was not built later than the beginning of VIII c.. In the VII c.ad there was the center and the powerful stronghold of the Western-Abkhazian principality of the Abazgs and later at the end of VIII c. the united Abkhazian kingdom was formed round its first capital Anakopia. Such status of Anakopia had suggested the existence of the powerful defensive structures here. The information about Anakopia is contained in the ancient Georgian written sources. When describing the events of XI c. After the Arab invasions the fortress of Anakopia is mentioned as the capital of Abkhaz kingdom. In XI c. Anakopia is mentioned again by the chronicle of Georgia and George Kedrin because of it becomes at that time an object of the Abkhaz-Byzantine clashes [3,4]. In 1046 year the King of the Abkhaz-Georgian kingdom Bagrat unsuccessful tried to take away this fortress from Byzantium. Anakopia was abandoned by Byzantium in the era of the reign of the king George II (1072-1089) of the Abkhaz-Georgian kingdom .
The beginning of the scientific study of the fortress dates back to the XIX century. The Frenchman from Switzerland Frederic Dubois de Montperay (1798-1850) the geologist, naturalist, archaeologist in 1833 noted the existence of the gate node and briefly mentioned the Gate round tower .The Gate tower is the most monumental construction of the second line of the defense and the fortress generally. At the first construction stage at the end of the 6th century the tower was consisted of two floors and the battle area which was framed by parapet with prongs. Its height from the top of the brick belt was 9,1 m. We can relate the reconstruction (the second construction phase) in the fortress of Anakopia with the time of the construction activity of the Abkhazian kings. At the end of IX c. for example it was the beginning of the government of the Abkhazian King Constantine III (893-922; 899-929 years) . His son George II (929-960) who had a title of the Master in the Byzantine table of ranks, the grandchildren Leon III and Dmitry III conducted the aggressive foreign policy and the active construction activity. Thus the second construction stage of the gate node was related by us with the Abkhazian Tsar George II and the building of the second line of defense (the first construction stage) of the fortress of Anakopia could be happened by the Emperor Justin II (565-578) soon after the conclusion of peace between Byzantium and Iranat the Transcaucasian Theater of Military Operations in VI c. after 565 year. The second line of defense is located below the citadel and consists of three fortress walls: the southern, western and eastern. The southern wall with seven towers which starts from the break of the gorge of the river Psyrtsha and obliquely crosses the gentle slope of the mountain, go down zigzag to the place where over the cliff of the gorge of the river Mysra there is large south-west corner tower is the most powerful of them. The input gate to the fortress is located behind the round south-west corner tower which is the most powerful of all towers of Anakopia, the details of which are given below. The tower reliably protected the gates of the fortress. An ancient narrow road approaching the gates of the fortress were at the base of the tower is slightly lower corner, skirting its left. The enemy was to pass here above a steep slope, being under massive attacks from the defenders of the tower, which struck him on the right side which was not covered by the shield.
The earliest description of the tower is associated with the visit of father Leonid who created the work “Abkhazia and the New Afon Simon-Kananit Monastery in it ” in Anakopia in 1880 year. The archeologist A. Bashkirov, who came at the invitation of the Abkhazian Scientific Society was the first specialist who researched the tower in 1924. He described in detail the round tower, noted its unusual arch which A. Bashkirov unreasonably called fan tracery and correlated it with European analogues and related the second construction stage of the tower to XIV-XV c.. In 1957-1958 years the complex Anakopian archaeological expedition under the direction of M.Trapsh was conducted, he described the tower and the gate node in detail, dated the second construction stage XI-XII c. based on existence in the tower the round pillar with the octahedral capital . And Y. Voronov described the Gate tower too . The most effective from the studies of the tower of the Soviet period was the work of V.G. Lekvinadze . He noted two construction stages in the tower, he dated the first stage (VII cent), denoted its analogs in Ahtala (Armenia) and Kekhvi (Ossetia) the similarity of its constructive methods with the Crimea, in detail described the finds of the decor inside the tower, fulfilled the scheme of graphic reconstruction of its interior, called the more ancient - "Romance" but not Gothic bearing the fin-arches of the tower, dated the second construction stage (XI-XIII c.). However, he, like all previous researchers made a number of inaccuracies: he mistakenly believed that the first vault of the tower is not from the arches of four but from the arches of five, the chip which he found defined as classical, but not as the disproportion ate capital (which is actually a wreck of the base of the column). Considering that when all denoted researchers visited the tower its first tier was covered with earth none of them took into account the central column installation method of the second construction stage directly on the bulk ground which led eventually to the collapse of arches. From 2014 y. the systematic archaeological (head O.Bgadjba)  and full-scale (head A. Argun) study of the object is held. It allowed obtaining the new scientific data.
Material and Method
In the opinion of all researchers originally the tower consisted of two floors and the battleground with merlons crowning it. Two fortress walls adjoined to it: one is from the north-east, and the other is from the north, the entrance to the tower was organized. The upper platform had exits at the battle moves of both walls which were equal to each other in height. The First floor (H-2,5m) had the full entrance from the north. It was used to store water, the provisions, possibly, and the weapons. The window opening of this tier was arranged on the east side as the coolest, according to the recommendations of Vitruvius. At the same time, a road which led to the tower and you could archery along it was seen from the window opening. There is adjoining to the wall, the hollowed and made cistern off the western facade of the wall on the site between the gates and the tower. It is for collection and storage of the rainwater, an area is about18 sq.m. The entrance to the lower tier when the gang way is lowered was through an aperture in the wall-barrier and was limited by the width of the gangway and an expanding wall. Outside, the level of the floor of the first tier is marked by anti-seismic belt from the large-sized flat brick four rows wide. The third tier of the tower was previously completed by a vault as evidenced by the remaining five imposts of the little arches from the limestone in the walls. The design of the arch was as follows: four bearing semicircular arches from carefully carved lime stone relied on the support in the center of the tower. The vault itself laid out by the arches was self-supporting. In X c. during the reconstruction the stone pillar was laid out in the center of the room and four arches in the center relied on it. A.V. Argun measured the fragment of the column. The brickwork of the vault itself was less neat and regular.
The located to the east are dual and have been made with an interval of 1,2m. In the interval there are no traces of the arch which indicates that in this place was a hole for the lifting to the fourth level. Also in this place have been arranged a platform (depth of 0,9m) in the thickness of the wall and 4 stone steps have been made for the lifting to the fourth level and as a transition to a thinner upper wall. The vaults and the arches have been folded from solid large parts and have been processed carefully. In the wall he arches rest on brackets with the characteristic oval bumps. The fourth tier of the tower also had a vaulted ceiling similar to the ceiling of the third tier. The bases and the parts of all four bearing arches and vaults with the imposts were preserved. From the fourth level there was the exit to the fighting path of the wall of the section of the gate leading to the gate. The exit was through a well-preserved carefully crafted opening which had a threshold. The opening has a semicircular jumper which is made of carefully fitted stone blocks, which is protruded on a quarter and a groove in the thickness of the wall for constipation. On the fourth level there is the fireplace on the southern part of the wall opposite the exit which led from the overbuilt western wall of the fortress. The fireplace is the most ancient from the monuments which were found in Abkhazia. From the fourth tier on the ladder you can get on the top platform of the tower, which has been fenced with parapet without prongs. The height of the parapet was about 1.4 m. In some places it was preserved to a height of 1.2 m. On the northern part there was an opening (width of 0.7 m.) in the parapet .
Measurement and examination of the column and the tower with the help of three-dimensional laser scanning convincingly showed that eight faces capitals of the column supported the upper vault, four arches rested on it. Later as a result of the collapse of the vault the column was two floors lower. Besides the modeling basing on scanning materials showed that the vault had exactly four arches. What previous researchers called the fifth arch was a bracket framing an exit to the vault. The design of the entrance to the vault as a whole has become clear.
Proceeding from the fact that the vaults of the third and fourth floors as well as the column which was between them had to prop up by another column which was lost now the search for the debris of the bottom column was undertaken. Five large fragments of the trunk and the necks of the now-lost column which were scattered at the foot of the tower outside were found and measured by us. The graphical analysis of wreckage revealed the diameter of the bottom column. It is equal to the diameter of the upper preserved column-1,02m.The base of the bottom column which has been profiled, has rounded form has been described and measured by V.G. Lekvinadze as capital. The cultural stratums were under the layer of destruction, they were not worried by the builders of the second stage from which the conclusion suggests that the bottom of the first floor they used as the base for the column. Perhaps the constructive error of the builder sand led to the shrinkage of the column which would inevitably lead to deformation and collapse of the entire structure.
Surely the vaults which were appearing at the second construction stage are the bright feature of the gate tower making it a unique architectural monument of medieval fortification architecture (Fig.1). It is worth mentioning that the remains of the vaults which are in tower have no analogues in the architecture of Abkhazia and the adjacent territories.
Each vault is formed by four complete semicircular ribs-by the arches which are relied on the column in the center. The self-supporting vault is laid out on these arches shaped like a torus. In the axils in the center and at the adjoining wall of the tower which were made by the vault the locking with stones which were laid on the wall and a vault like a false vault were made. The source of such a vault can be considered the reception of a two-story arcade on the columns which is widespread in the capital of Byzantium. This design was often carried out in the imperial buildings such as the tank Yerbata in Constantinople. For the execution of the vault of the round tower in Anakopia the master cut out a fragment of such an arcade. A similar interpretation is found in a number of towers in Turkey (Chesme, Mamuri, Ajazuluk). Here the walls are built over four arch-ribs, it comes out crosswise, on which the flat overlapping are relied over above. At the same time in these towers such vault is made in one level. The vault of the Anacopian tower as a type of the construction is not represented in any edition and research dedicated to the Byzantine building technologies. Such vault is not found by us in other later buildings.
Given all of the above, it can be assert that the vault of the round tower in Anakopia is unique and consequently was not built on the model, like the tower itself. For this vault it is proposed to introduce a typological term and call it "Abazgh”.
To determine the concept of restoration, of course it is necessary nevertheless to consider more in detail the analogs of the gate tower (Fig.1). The tower before the gate in Akhtala is the nearest, the well-preserved monument but here the column is rectangular and differs greatly in the form and quality of the design of the blocks with the Anakopian. Their plastic outer lines, the presence of a high parapet around the upper platform and the opening in it which is directed to the fortress wall and also the presence of a privileged tier especially these towers are related to Anakopian. Despite the proximity of the technical execution the towers of Akhtala and Anakopia, hinting at one artel of builders, we refute the opinion of V.G. Lekvinadze, that the tower of Akhtala was a parallel of the Gate Anakopian tower. The reconstruction was carried out by an international brigade of builders, with an orientation on the towers-analogues (in the form, the construction and structural techniques, masonry techniques, etc.),which were located on the territory of the Byzantine Empire and now they are in Turkey, Greece and Armenia. Separate architectural and construction methods from indicated areas were brought by the masters on invitation. For this reason the round columns which are crafted in the most careful manner including with the capital with eight facets are appeared in the Gate tower.
The question of dating analogs seems extremely important. V.G. Lekvinadze dates the tower of Kekhvi earlier XV-XVI c., the tower in Akhtala - XII-XIII c. He names Akhtala the Georgian monastery, probably for political reasons of his time. The greatest similarity is observed with the tower in Akhtala: the presence of a stone pillar in the center and the leaning arches on it; the presence of several levels which are strung on the pillar; the arches are bearing, the coating of the vault itself leans on the mand it is self-supporting; the arches themselves are laid out from well-cut stones of the local limestone and have the same characteristic rollers in the place of the transition of the bracket in the wall. Both input nodes have the tier of the tower with prongs. There is the great similarity in the geometry of the entasis of the outer walls of towers, in their proportions and the nature of the masonry; and there, and there the central column is laid out from the large stone blocks, it has the square form, rather than round form only in Akhtala with the large torn seams. There is something common that the tower of Kehvi has and the Anakopian tower has too-this is the fireplace. It is on the basis of the fact that the column is round V.G. Lekvinadze makes the assumption of an earlier (X century) reconstruction of the tower being guided by on round towers VI c. in Chersonese. Thus, the question of the dating of analogues is very important for solving many issues of the restoration of the Anakopian tower.
The tower in Akhtala was adopted as the main analogue. In X c. the fortress of Ptghavank (Akhtala) became the most important strategic point of the kingdom of Kurikian-Bagratid . In X-the beginning of XI c. Anakopiya had very close ties with Byzantium and dynastic ties with Armenia . Byzantine construction policy supposed the presence of interethnic building brigades. The similarity of the construction and compositional techniques of the towers of Akhtala and Anakopia can be explained by the fact that in their construction the same masters participated.
The interesting reasoning can be done about that at "reconstruction" X c. the tower was made namely with the central column. This method, quite rare for the Byzantine Empire is very ancient for the mountain peoples of the Caucasus. The central pillar was from time immemorial was distributed in the Caucasian dwelling-Armenian, Ossetian, Georgian, Vainakh. The central support pillar had besides the constructive also a special symbolic meaning: the pillar is the symbol of the genus. The pillar or the pillars served as a means of marking of the semantic center of the dwelling. The first value of the column as in the space of the dwelling and in the natural space is associated with the mythological image of the world tree. The second is the identification of the image of the world tree with the goddess of the sky and then with the woman deity, the symbol of the genus in the age of matriarchy. The similarity of construction techniques with other regions is observed in the arches, bearing the vault and in the wall brackets. These arches are brackets in X-XI c. were very common in the one-apsidal temples of the region- in Armenia, in Alania, in Serir (Dagestan), in Nakhch (Ingushetia) .
As an inference, we can say that on the basis of the character of the masonry, the round form, the presence of the column inside, on which the vault with ribs is leaning, of the analysis of the documents obviously, that all the above analogs, except Kekhvi, belong to one time of X-XI c. and perhaps, to one generation of builders.
Summing up, we can state the novelty of basic scientific provisions compared with previous studies of the round tower of Anakopia: authentically is proved that the surviving column was on the fourth tier and there was the lower column which was relied on the rammed earth of the backfilled tier of VI c., had a base and a capital; a new type of the vault of the Byzantine period was discovered and designated as "Abazgh", its geometry and construction were determined for sure; simultaneous analogues of the tower were found in Armenia, Turkey, Greece.
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