The area around Wartau was first settled around 9000 years ago, culminating in neolithic settlements on the nearby Ochsenberg and Prochna Burg at about 3000 BC. A Merovingian fortress was built at Prochna Burg, but was destroyed around 750. While there are no written records that mention the first owner of the castle or when it was built, the wooden beams in the castle have been dated to about 1225. It was probably built as an administrative center for royal estates in the area. It may have been built by the Graubünden Freiherr von Sagogn, because around 1320 it was inherited by Count Hugo III von Werdenberg-Heiligenberg from the Freiherr von Wildenberg who was related to the Freiherr vonf Sagogn.
The castle first appears in the historical record in 1342 when Johannes von Belmont pledged it to his wife Adelheid von Klingen in exchange for 250 silver marks. In the following decades the Belmont family fought the Werdenberg-Heiligenbergs until the death of Ulrich Walter von Belmont in 1371 and the extinction of the Belmont family. The castle probably returned to the Werdenberg-Heiligenberg family and was occupied by their vassals for the next couple decades. Around 1390 the castle was owned by the related Werdenberg-Sargans. In 1393 as the two families fought for territory, the castle was besieged for eleven days. In 1399 it returned to the Counts of Werdenberg-Heiligenberg.
During the 14th century the castle was expanded several times, but by the 15th century it began to be neglected. In 1414 Count Rudolf II sold Wartau to his cousin Count Friedrich VII of Toggenburg, but six days later converted the sale into collateral for a loan. The Counts of Werdenberg-Heiligenberg died out in 1428, before they could redeem the loan. Eight years later Friedrich VII died, ending the Toggenburg line and starting the Old Zürich War over the Toggenburg inheritance. After the war it was inherited by the Freiherr von Thierstein, but after their extinction it passed through the von Limburg, Montfort-Tettnang and Sax-Misox families before it was sold in 1485 to the city of Lucerne. However, Wartau was too far from Lucerne and in 1493 they sold it to the Barons of Kastelwart. The Barons were faithful supporters of the Habsburgs, which caused conflicts with the villagers who supported the Swiss Confederation. In 1498 they sold the castle and lands to the Swabian von Hewen family. In the following year Matthias von Kastelwart died in the Battle of Dornachagainst the Swiss. In 1517 the Hewen family sold the castle and lands to the Canton of Glarus. However, the Glarus appointed Landvogt lived at Werdenberg Castle and so the castle at Wartau lost its administrative role and was abandoned around 1530.
Following the collapse of the Helvetic Republic and the creation of the Canton of St. Gallen in 1803, Wartau became part of the new Canton. The castle ruins were sold in 1818 to a private owner. It was donated to the municipality in 1911 and restored in 1932. In 1982 it was again repaired and restored, followed by a survey and excavations in 2002.
The castle consists of either two square towers built next to each other or a single rectangular tower which was divided into two. The north-eastern tower was about four stories tall, while the south-western tower was lower and divided into apartments. Around 1300 a crenellated parapet was added around the top of both towers. In the 14th century an additional story was added to the top of both towers along with new parapets and a flat roof. The new upper story is still visible as it was built from different stone. Around 1500 the upper story was rebuilt. The castle is surrounded on three sides by a ring wall, which ran along a steep cliff.References:
Bergenhus fortress is one of the oldest and best preserved castles in Norway. It contains buildings dating as far back as the 1240s, as well as later constructions built as recently as World War II. The extent of the enclosed area of today dates from the early 19th century. In medieval times, the area of the present-day Bergenhus Fortress was known as Holmen (The islet), and contained the royal residence in Bergen, as well as a cathedral and several churches, the bishop's residence, and a Dominican monastery. Excavations have revealed foundations of buildings believed to date back to before 1100, which might have been erected by King Olav Kyrre. In the 13th century, until 1299, Bergen was the capital of Norway and Holmen was thus the main seat of Norway's rulers. It was first enclosed by stone walls in the 1240s.
Of the medieval buildings, a medieval hall and a defensive tower remain. The royal hall, today known as Haakon's Hall, built around 1260, is the largest medieval secular building in Norway. The defensive tower, known in the Middle Ages as the keep by the sea, was built around 1270 by King Magnus VI Lagabøte, and contained a royal apartment on the top floor. In the 1560s it was incorporated by the commander of the castle, Erik Rosenkrantz, into a larger structure, which is today known as the Rosenkrantz Tower.
In the Middle Ages, several churches, including the Christ Church, Bergen's cathedral, were situated on the premises. These however were torn down in the period 1526 to 1531, as the area of Holmen was converted into a purely military fortification under Danish rule. From around this time, the name Bergenhus came into use. Building work on the Christ Church probably started around 1100. It contained the shrine of saint Sunniva, the patron saint of Bergen and western Norway. In the 12th and 13th centuries it was the site of several royal coronations and weddings. It was also the burial site of at least six kings, as well as other members of the royal family. The site of its altar is today marked by a memorial stone.
In the 19th century, the fortress lost its function as a defensive fortification, but it was retained by the military as an administrative base. After restoration in the 1890s, and again after destruction sustained during World War II, Bergenhus is today again used as a feast hall for public events. During World War II, the German navy used several of its buildings for their headquarters, and they also constructed a large concrete bunker within the fortress walls. The buildings, including the Haakon's Hall, were severely damaged when a Dutch ship in the service of the German navy, carrying approximately 120 tons of dynamite, exploded on 20 April 1944 in the harbour just outside the fortress walls, but the buildings were later restored.
Bergenhus is currently under the command of the Royal Norwegian Navy, which has about 150 military personnel stationed there. The fortifications Sverresborg fortress and Fredriksberg fortress also lie in the centre of Bergen. Haakon's Hall and the Rosenkrantz Tower are open for visits by the public. Koengen, the central part of Bergenhus Fortress is also known as a concert venue.