The Kajaani castle was built on the Ämmäkoski island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 of the Kajaani river

Kajaani River

Kajaani River is a river in the Province of Oulu and in the region of Kainuu, Finland.The river runs from Lake Nuasjärvi to Lake Oulujärvi through the city of Kajaani. From there the waters flow trough the Oulujoki river into the Gulf of Bothnia. The river drains a chain of lakes that originates...

 in the centre of Kajaani

Kajaani

Kajaani is a town and municipality in Finland.It is the capital of the Kainuu region. It is located southeast of Oulujärvi , which drains to the Gulf of Bothnia along the Oulujoki . There are inhabitants and city surface area is of which is water. The population density is . The town is...

, Finland

Finland

Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, in the century.

The castle functioned as an administrative centre, a prison

Prison

A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime...

, and a military strongpoint. The most famous prisoner in the castle was the historian Johannes Messenius

Johannes Messenius

Johannes Messenius was a Swedish historian, dramatist and university professor. He was born in the village of Freberga, in Stenby parish in Östergötland, and died in Oulu, in modern-day Finland.-Childhood:...

, who was forced to live in the poor conditions of the castle from 1616 to 1635.

Construction of the Kajaani castle began in 1604 and was completed in 1619. At first the castle only consisted of a stone

Rock (geology)

In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 wall, two round towers, and wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

en buildings at the yard inside the castle.

Count Peter Brahe ordered a second construction stage of the castle, which was started in the 1650s and completed in 1666. During this construction stage, many wooden structures of the castle were replaced with stone structures to form a fortress.

During the Great Northern War

Great Northern War

The Great Northern War was a conflict in which a coalition led by the Tsardom of Russia successfully contested the supremacy of the Swedish Empire in northern Central Europe and Eastern Europe. The initial leaders of the anti-Swedish alliance were Peter I the Great of Russia, Frederick IV of...

 (also known as the "Greater Wrath"), Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n forces sieged the castle for several months, until it was finally forced to surrender because of lack of food, firewood and ammunition. Shortly after this, the Russians exploded the castle and its inhabitants were transported to Russia to be imprisoned.

In 1917 a hydro-electric plant was built at Ämmäkoski.

The first wooden bridge on top of the ruins was built in 1845. By 1937 the castle-island became a fundament for a new road-bridge made of concrete.

The bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

 called Linnansilta ("castle bridge") was originally the only bridge across the Kajaani river. After the construction of later bridges, the traffic on Linnansilta has reduced and the authorities have drafted plans to take down the bridge and give this national monument a due and proper restoration.

Trivia

• The Kajaani castle is considered to be the smallest stone-castle in Europe and the northernmost castle in the world.
• The castle figures in the novel The Czar's Spy, by William Le Queux
  William Le Queux
  William Tufnell Le Queux was an Anglo-French journalist and writer. He was also a diplomat , a traveller , a flying buff who officiated at the first British air meeting at Doncaster in 1909, and a wireless pioneer who broadcast music from his own station long...
  
  , where it is a terrifying prison held by the Russians who occupy Finland.
• Drawing of Kajaani Castle, made 1732