The Architecture of the Tarnovo Artistic School is a term for the development of architecture during the Second Bulgarian Empire (1185–1396). In the 13th and 14th centuries the capital Tarnovo determined the progress of the Bulgarian architecture with many edifices preserved or reconstructed which show the skills of the Medieval Bulgarian architects and the construction and decorative techniques they used. The builders have created a unique architectural style, known as Tarnovian Style (Tarnovo style), that influenced the architecture in many countries of Southeastern Europe and parts of Central Europe. With its diverse architecture, the Tarnovo School may be separated into several branches according to the function of the buildings.
Religious architecture
Design
During the Second Bulgarian Empire the churches did not have large or complicated designs because they were intended to be a place of penance. Typical of the Tarnovo School of Architecture were relatively small cruciform dome churches or basilicas. At the expense of its small length and width, the churches rose to height. They were often built over a stone base around one meter high. As a principle the main entrance was located to the west. After the doorway followed the pritvor (narthex), the naos and the altar. A small rectangular bell-tower sometimes rose above the narthex ("St Dimitar of Solun" in Tarnovo, the Church in the Asenova krepost in Asenovgrad, the Church of Christ Pantocrator in Nessebar and others). The naos could be separated into naves (in the basilicas) with columns or pillars. According to the number of naves the churches were one-naved (Church of St Demetrius of Thessaloniki, Veliko Tarnovo in the Asen's Neighbourhood, Tarnovo, Boyana Church), two-naved ("St Ivan of Rila" in Trapezitsa, Tarnovo) and three-naved (SS. Forty Martyrs Church in Tarnovo, "St Nicola" in Melnik). In the cruciform dome churches (Church of St John Aliturgetos and Church of Christ Pantocrator, both in Nessebar) the dome lied over four columns which were connected to the walls with arches. The altar was formed by a semicircular or polygonal apse. In some churches the altar was separated into three parts and the external ones (called bema and diakonnik) were used for safe-keeping of the church plates, garments and books. In that case there was usually a triple apse. The design was complicated by a pre-apse space. The vaults were semicircular and built of bricks. Some churches had outhouse parts such as galleries (SS. Forty Martyrs Church and "St Peter and Pavel" in Tarnovo), chapels (Boyana Church), ossuaries and others. The Church "St Virgin Maria of Petrich" in the Asenova krepost has two stories and the lower one served as an ossuary."Старобългарско изкуство", Том ІІ - Никола Мавродинов, издателство "Наука и изкуство", София, 1959 г.
A peculiar type of Christian churches were those with a triconch plan. They are small, one-naved with or without a narthex. Their main peculiarity were the three conchas (apses) placed in the eastern, southern and northern walls of the naos. The small dome is laid directly on the walls. The conchal churches can be found mainly in the monasteries and are not so exquisite. Examples include the church in the "St Archangels" Monastery in Tran, "St Nicola Mrachki" in the Peshterski Monastery and others.
Decorative ornaments
The main feature of the Tarnovo School of Architecture is the rich decorative ornamentation in exterior of the edifices. The technique that was used was called mixed construction in which belts of stone and bricks alternated with each other. That method was a heritage from the Roman architecture (opus mixtum) but in that case it had lost its initial constructive application and was used mainly with artistic purpose. The wide plaster fugues also had decorative purpose. The builder chose different types of stone (limestone, travertine, marble, granite), and the bricks had varied shape and dimensions and were put in different positions forming decorative ornaments and monograms. A cell type method was sometimes used in which each stone block was completely surrounded by bricks. The bricks were painted in red in order to increase the contrast. The facades of the churches were segmented by deep niches (often with two steps) decorated with flying buttresses and archvaults. Unlike the churches in Constantinople the niches from the Tarnovo School of Architecture do not respond to the interior (pseudo constructive niches) and were used for purely decorative purpose. As an additional decoration rows of clay circles and four-leaves glazed in green, brown, yellow or orange were used. The origins of that type of decoration are in the Arab architecture. The Nessebar churches "St John Aliturgetos" and "Christ Pantocrator" have especially sumptuous decoration.
Sometimes the architects used painting to decorate certain elements. The lunettes of the niches of St Dimitar of Solun Church in the capital were plastered up and painted with rhomboid patterns. High on the walls in some churches consoles were built in on which laid small decorative arches. The roofs were covered with tiles or lead plates (the initial cover of St Peter and Pavel in Tarnovo), the dome was narrow and high with circular or polygonal shape. The polygonal domes were characterized with small columns on the corners. The appearance of the churches was complemented with sculptures and paintings.
Monasteries
During the 13th and especially during the 14th centuries the construction of monasteries thrived. Small monasteries such as the SS Forty Martyrs Monastery as well as large monastery complexes were constructed. Due to the troubled times many monasteries resembled fortresses. They usually had rectangular shape, the buildings surrounded a yard in which the main church was located. From the outside they had high stone walls reinforced with counterforts, and from the inside there were galleries with several stores which led towards the dwellings of the monks. The monastery complexes also included farm buildings, stores and workshops. Examples of that type are the Zograf Monastery in Athon; Bachkovo Monastery near Asenovgrad or the Rila Monastery. Although destroyed several times, the overall plan of the later follows the traditions of the Second Bulgarian Empire.
With the growing influence of the Hesychasm, during the 14th century the rock monasteries became widespread. The monk's dwelling and the churches were directly hewn into the rocks. Wooden balconies and stairs were added from which only the cradles in the rocks have survived. That type of monasteries were mainly built in north-eastern Bulgaria along the rivers Ruse Lom, Black Lom and White Lom.
The largest concentrations of monasteries in medieval Bulgaria were in northern Stara Planina especially around the capital; in the areas to the north and south Sofia; the southern Black Sea coast; the area around Pirot and in Macedonia. Many of these were called the small Mount Athon.
Military architecture
During the Second Empire the fortresses were usually built on locations which were difficult to access (hills or plateaus) and thus they sharply differed from the monumental construction in the north-east of the country from the period of the First Bulgarian Empire. The walls of the fortresses were built from stones welded together with plaster; they had two faces and the space between them was filled with a mixture of gravel and plaster (blockage). A wooden scaffolding was built from the inside which protected the walls from collapse until the blockage dried up. The height and thickness of the walls varied depending on the terrain and in the different parts of one castle complex they could vary. The top of the walls and the towers had pinnacles. Counterforts were used as additional protection from landslip.
The tower varied in shape: square, rectangular (the tower in Cherven), circular, oval, triangular, horseshoe-shaped or with irregular shape. Depending on their position and functions they were: entrance, defense, edge or water towers. The later were towers-wells, located in the immediate vicinity of a river in such a way that their foundations soaked up water. The immense fortress Tsarevets in Tarnovo had such water towers. They could be reached by vertical walls from the main stronghold with secret galleries. They were extremely useful during long sieges. In the most difficult place to access in the fortress stood the citadel: a separate rampart in case the outer areas were overrun by the enemy. Examples of such citadels can be found in the castles of Shumen, Lovech, Cherven, Ohrid, Devol"Каменните щитове" - Борис Чолпанов, "Военно издателство", София, 1989 г. and others. As an additional defense some castles had water-filled moats. A fine example of this is Baba Vida in Vidin. In many cases such moat were of no need due to the fine positioning of the fortress. The Yantra river makes double curve around the two main fortresses in the capital Tarnovo, Tsarevets and Trapezitsa and served as a natural water obstacle. Many other castles were protected in a similar way such as Cherven or Prosek. Some seaside strongholds (Kaliakra, Nessebar) also had a natural water barrier.
Sometimes the steep rocks were enough defense and walls were built only in vulnerable places. An example of such type of fortress is the Belogradchik Fortress. Often these ramparts looked like ordinary plateaus or hills and hence they were called "hidden fortresses". Many strongholds if that type guarded the mountain passes of Stara Planina between Moesia and Thrace.
A peculiar type of defensive facility was the pirgos (a single tower) called in Western Europe dungeon. It was built inside the fortress without any links to the other edifices. It served as a last refuge for the defenders in case the other parts of the fortress had fallen. Examples for pirgos in the country are the ruins in Matochina (near the Tundzha river), the tower in the Sadovo monastery and the Tower of Hrelyo in the Rila monastery built in 1335 which is completely preserved. It is 23,60 meters high and has five storeys. A cellar is located in its foundations. There was also a well which supplied the defenders with fresh water during sieges. Reinforced counterforts supported the tower. They merge with brick arches and serve as a base for the Transfiguration of God Chapel located at the top of the tower. Most of the pirgos usually had four or five storeys. In the monastery pirgos the most valuable objects (the treasury and the donations) were kept as well as the library.
Military architecture had purely functional purpose. The builder did not follow aesthetic criteria and rarely constructed decorative elements on the fortifications. In fact many castles were part of large defensive systems which covered the frontier regions or ran along the middle of the country. The most important fortification systems were along the Danube to the north, Stara Planina in the Middle, Black Sea to the east, the Rhodopes to the south and Macedonia to the south-west. Apart from the capital Tarnovo, the major Bulgarian fortresses included Vidin, Silistra, Shumen, Cherven, Lovech, Sofia, Plovdiv, Lyutitsa, Ustra, Ohrid, Skopie, Bitola and many others.
Palace construction and urban planning
The defensive system of Tarnovo was impressive. The Medieval capital had three fortified hills: Tsarevets, Trapezitsa and Momina Krepost (Devingrad). Numerous monasteries nestled on the Sveta Gora heights. Between the hills were situated several neighbourhoods: the New City (Asenova mahala); the quarter of the foreign merchants (Frazgrad) and the Jew quarter; they were all surrounded by walls. The palaces of the emperors and the patriarch were located on the most heavily fortified hill, Tsarevets and both resembled a small citadel in way.