The Kalozha church of Saints Boris and Gleb is the oldest extant structure in Hrodna. It is the only surviving monument of ancient Black Ruthenian architecture, distinguished from other Orthodox churches by prolific use of polychrome faceted stones of blue, green or red tint which could be arranged to form crosses or other figures on the wall.
The church is a cross-domed building supported by six circular pillars. The outside is articulated with projecting pilasters, which have rounded corners, as does the building itself. The ante-nave contains the choir loft, accessed by a narrow gradatory in the western wall. Two other stairs were discovered in the walls of the side apses; their purpose is not clear. The floor is lined with ceramic tiles forming decorative patterns. The interior was lined with innumerable built-in pitchers, which usually serve in Eastern Orthodox churches as resonators but in this case were scored to produce decorative effects. For this reason, the central nave has never been painted.
The church was built before 1183 and survived intact, depicted in the 1840s by Michał Kulesza, until 1853, when the south wall collapsed, due to its perilous location on the high bank of the Neman. During restoration works, some fragments of 12th-century frescoes were discovered in the apses. Remains of four other churches in the same style, decorated with pitchers and coloured stones instead of frescoes, were discovered in Hrodna and Vaŭkavysk. They all date back to the turn of the 13th century, as do remains of the first stone palace in the Old Hrodna Castle.
In 2004, the church was included in the Tentative List of UNESCO's World Heritage Sites.References:
From its origin as a small stronghold built by the ancient Illyrian tribe Dalmatae, becoming a royal castle that was the seat of many Croatian kings, to its final development as a large fortress during the Ottoman wars in Europe, Klis Fortress has guarded the frontier, being lost and re-conquered several times. Due to its location on a pass that separates the mountains Mosor and Kozjak, the fortress served as a major source of defense in Dalmatia, especially against the Ottoman advance, and has been a key crossroad between the Mediterranean belt and the Balkan rear.
Since Duke Mislav of the Duchy of Croatia made Klis Fortress the seat of his throne in the middle of the 9th century, the fortress served as the seat of many Croatia"s rulers. The reign of his successor, Duke Trpimir I, the founder of the Croatian royal House of Trpimirović, is significant for spreading Christianity in the Duchy of Croatia. He largely expanded the Klis Fortress, and in Rižinice, in the valley under the fortress, he built a church and the first Benedictine monastery in Croatia. During the reign of the first Croatian king, Tomislav, Klis and Biograd na Moru were his chief residences.
In March 1242 at Klis Fortress, Tatars who were a constituent segment of the Mongol army under the leadership of Kadan suffered a major defeat while in pursuit of the Hungarian army led by King Béla IV. After their defeat by Croatian forces, the Mongols retreated, and Béla IV rewarded many Croatian towns and nobles with 'substantial riches'. During the Late Middle Ages, the fortress was governed by Croatian nobility, amongst whom Paul I Šubić of Bribir was the most significant. During his reign, the House of Šubić controlled most of modern-day Croatia and Bosnia. Excluding the brief possession by the forces of Bosnian King, Tvrtko I, the fortress remained in Hungaro-Croatian hands for the next several hundred years, until the 16th century.
Klis Fortress is probably best known for its defense against the Ottoman invasion of Europe in the early 16th century. Croatian captain Petar Kružić led the defense of the fortress against a Turkish invasion and siege that lasted for more than two and a half decades. During this defense, as Kružić and his soldiers fought without allies against the Turks, the military faction of Uskoks was formed, which later became famous as an elite Croatian militant sect. Ultimately, the defenders were defeated and the fortress was occupied by the Ottomans in 1537. After more than a century under Ottoman rule, in 1669, Klis Fortress was besieged and seized by the Republic of Venice, thus moving the border between Christian and Muslim Europe further east and helping to contribute to the decline of the Ottoman Empire. The Venetians restored and enlarged the fortress, but it was taken by the Austrians after Napoleon extinguished the republic itself in 1797. Today, Klis Fortress contains a museum where visitors to this historic military structure can see an array of arms, armor, and traditional uniforms.