The Franziskaner-Klosterkirche was founded in 1250 in the early Gothic style as a monastery church for a Franciscan house. It was a fieldstone church, 52 metres long and 16 metres wide. Its remains can be found in the north wall of the present ruins. This was replaced with a three-aisled brick basilica church, begun at the end of the 13th century and completed in the first half of the 14th century, whose ruins still survive. In 1365 Louis II, Elector of Brandenburg was buried there. Around 1500 it was renovated.
The monastery was closed due to the Protestant Reformation's arrival in Berlin in 1539. None of the monastic buildings survive, though some of them housed Berlin's first printing press from 1571 and the Evangelisches Gymnasium zum Grauen Kloster from 1574. Pupils and teachers at the latter included Karl Friedrich Schinkel and Friedrich Ludwig Jahn, whilst Otto von Bismarck also visited the church. Leonhard Thurneysser ran the printing press and also restored the church between 1583 and 1584.
Small modifications were made in the second half of the 17th century, such as demolishing the old staircase tower, building a new timber staircase on the west side and in 1712 demolishing the rood screen separating the nave from the chancel. 1712 also saw a fire in the church's roof and in 1719 the church was restored, raising the floor level by 1 metre and bricking up two northern choir windows.
Extensive renovations were carried out in the first half of the 19th century - the gabled tower was demolished in 1826, two new towers were built on the west side in 1842, a new sacristy was built and the floor lowered again. Plans were produced for the work by Karl Friedrich Schinkel, Christian Gottlieb Cantian and the former track-inspector Berger was preceded by the construction work - Berger's second design was that ultimately implemented. Work lasted until 1845, though the church was closed due to severe damp in its masonry in 1902 and in 1926 most of the 19th century changes were reversed. The church was re-consecrated on 24 May 1936.
The church was destroyed on 3rd April 1945 in the bombing of Berlin in World War II. In 1950 the debris was removed and the church ruins secured between 1959 and 1963, although the ruined monastic buildings were demolished completely to make way for a park. The ruins were restored again in 2003-2004 and are now used for exhibitions, plays and concerts.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.