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Suomenlinna
Suomenlinna is an old stone fortress built on islands in the sea near Helsinki, Finland. Today about 800 people live there, in the old fortress!
Suomenlinna is a sea fortress on a group of islands off Helsinki, Finland. Work on it began in 1748, when the area belonged to Sweden. Its stone walls, grassy ramparts and pointed bastions spread over six islands, and today it is a part of Helsinki where people live and visitors explore.
Suomenlinna (Sveaborg in Swedish, Viapori in Finnish) is a sea fortress begun in 1748 on islands off Helsinki under the Swedish officer Augustin Ehrensvärd, who adapted Vauban's bastion system to the rocky site. Covering 210 ha of six islands with some 200 buildings and 6 km of walls, it served Sweden, the Russian Empire and Finland, passed to civilian use in the 1970s and was inscribed as a World Heritage Site in 1991.
Photo: Michal Pise, CC BY 2.0, via Wikimedia Commons
Discover Suomenlinna
Suomenlinna is in Finland, a country in the north of Europe. It is built on islands in the sea, close to the city of Helsinki.
It is a fortress: a strong place with thick walls.
Suomenlinna is a sea fortress built on a group of islands just off Helsinki, the capital of Finland. It covers 210 hectares across six islands, with about 200 buildings and 6 kilometers of walls.
Today it is one of Helsinki's districts. Its official website says about 800 people live there and about 400 work there, and UNESCO calls it one of the most popular tourist attractions in Finland.
UNESCO describes Suomenlinna as a sea fortress built gradually from 1748 on a group of islands belonging to Helsinki, covering 210 ha over six islands, with 200 buildings and 6 km of defensive walls. It was inscribed in 1991 under criterion (iv), as an outstanding example of the general fortification principles of the 17th and 18th centuries, notably the bastion system.
The fortress's governing body notes that Suomenlinna is now a district of Helsinki, home to about 800 residents and a workplace for about 400 people, and one of the most popular tourist attractions in Finland.
- Where
- islands off Helsinki, Finland
- Built
- from 1748
- Size
- 210 ha on six islands
- World Heritage
- inscribed 1991
A fortress for three countries
Long ago, in 1748, builders started making the fortress for the Kingdom of Sweden.
Later it belonged to Russia, and then to Finland.
Work on the fortress began in 1748, in what its official history calls the Swedish era. In 1750 it was named Sveaborg, which became Viapori in Finnish. A dry dock was built there for making ships.
The fortress later belonged to the Russian Empire. In 1918, after Finland became independent, it was renamed Suomenlinna, which means 'Castle of Finland'.
The official history says work began in 1748 on the Susiluodot islands, the fortress was named Sveaborg (Viapori) in 1750, and a dry dock was started for building ships for the Archipelago Fleet. The plans were soon scaled back, and the active phase of building ended just over 40 years after it began; the fortress was never completed as first planned.
UNESCO notes that the fortress served three states in turn: the Kingdom of Sweden, the Russian Empire and the Republic of Finland. In 1918 it was renamed Suomenlinna, 'Castle of Finland', and in the early 1970s it passed from the army to civilian administration.
Bastions on the rocks
The fortress walls are made of rock from the islands. They have pointed corners called bastions.
Grass grows on top of many of the walls.
The fortress was built from local rock. Its walls have bastions: pointed corners that stick out from the walls. The work was led by Augustin Ehrensvärd, a Swedish officer, who fitted the bastion design to the rocky islands.
In the 1800s, more barracks and other buildings were added, and the defenses were updated.
UNESCO credits the Swedish admiral Augustin Ehrensvärd (1710–1772) with supervising the work and adapting Vauban's theories to the region's very special geography. The original fortress was built of local rock and fortified with a system of bastions over varied terrain, with a dry dock for the fleet.
During the 19th-century Russian period, barracks and other buildings were added and the defensive system was adapted to the needs of a modern fortress. UNESCO notes that most fortifications and utilitarian buildings of the Swedish and Russian periods are well preserved.
Living in a fortress
Today people live in the old fortress buildings! Their homes are in the fortress.
Many visitors come to explore it, too.
After the army left in the early 1970s, the old buildings were repaired to become homes, workplaces, services and places for culture. Builders have used traditional methods to keep the fortress's character.
Today Suomenlinna is a district of Helsinki where about 800 people live, and many visitors come to explore its walls and islands.
Since the fortress became a residential area, UNESCO notes, buildings have been renovated as apartments, workspaces, private and public services and cultural spaces, with traditional construction methods favored to protect its values.
UNESCO lists a sharp rise in sea level or increased rainfall as possible threats to the property. Most of the historic buildings are owned by the Governing Body of Suomenlinna, a government agency under Finland's Ministry of Education and Culture.
- Walls
- 6 km
- Buildings
- about 200
- People living there
- about 800
Walls by the sea
In this photo, a long stone wall stands on pink rocks by the sea. Can you find the little red and white tower?
This photo was taken on 7 June 2005. It shows a long stone wall with arched openings, standing on reddish rocks at the water's edge. Behind it rise grass-covered earth walls, with paths winding between them.
A small red and white beacon stands on the rocks in front, and the city can be seen far away across the water.
The photograph (7 June 2005, by Michal Pise; a Commons Picture of the Day) shows a stretch of stone curtain wall with arched openings on the shore rocks, grass-covered ramparts and bastions behind it with footpaths between them, a red and white navigation beacon in front, and a distant city skyline across the water.
UNESCO notes that the fortifications, the buildings of different eras and their surroundings together keep Suomenlinna's character, in materials, methods and architecture.
Amazing facts
-
About 800 people live in this old fortress today!
Suomenlinna is one of Helsinki's districts, home to about 800 people and a workplace for about 400.
The governing body reports about 800 residents and about 400 people working on the islands.
-
The builders hoped to finish in four years, but it never got finished as planned!
The plan was to finish the fortress in only four years, but it was never completed as first planned.
The original aim was completion in four years; the active fortification work ended just over 40 years after it began, short of the original plan.
-
The name Suomenlinna means 'Castle of Finland'!
In 1918 the fortress got the name Suomenlinna, which means 'Castle of Finland'.
Renamed Suomenlinna ('Castle of Finland') in 1918, the fortress was earlier called Sveaborg in Swedish and Viapori in Finnish.
Words to know
- fortress
- a large, strong building or group of buildings made to protect a place
- bastion
- a pointed part of a fortress wall that sticks out from the main wall
- rampart
- a thick wall of earth and stone around a fortress
- dry dock
- a basin that can be emptied of water so ships can be built or repaired inside
- district
- one part of a city
- beacon
- a light or marker that helps ships find their way
Discovery challenge
-
Where is Suomenlinna built?
On what is the fortress of Suomenlinna built?
Across how many islands does the fortress stretch?
- On islands in the sea
- On a mountain top
- In a desert
Show the answer
On islands in the sea
On islands in the sea!
On a group of islands off Helsinki.
Six islands.
-
When did builders start the fortress?
In which year did work on the fortress begin?
In which year did Sweden begin the fortress on the Susiluodot islands?
- 1748
- 1918
- 1991
Show the answer
1748
In 1748!
1748.
1748.
-
What does the name Suomenlinna mean?
What does 'Suomenlinna' mean?
What does the name given in 1918 mean?
- Castle of Finland
- Island of Birds
- Big Harbor
Show the answer
Castle of Finland
Castle of Finland!
Castle of Finland.
Castle of Finland.
-
What are the pointy corners of the fortress walls called?
What are the pointed corners that stick out from the walls called?
Which fortification system, after Vauban, did Ehrensvärd adapt to the islands?
- Bastions
- Bridges
- Chimneys
Show the answer
Bastions
Bastions!
Bastions.
The bastion system.
-
Do people live in Suomenlinna today?
About how many people live in Suomenlinna today?
About how many residents does the governing body report?
- About 800
- Nobody
- About 80,000
Show the answer
About 800
Yes, about 800 people!
About 800.
About 800.
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For parents & teachers
What children will learn
- Explain what a bastion is and find bastions in a photo of a fortress.
- Describe how an old fortress can be reused as a neighborhood with homes and workplaces.
- Explain how builders fit a standard design to a particular landscape, like rocky islands.
Recommended ages: 4 to 17 · About 15 minutes
Talk about it
- People live in Suomenlinna today, inside an old fortress. What would be fun or hard about living there?
- The fortress was planned to take four years but was never finished as planned. Why do big projects often take longer?
- The fortress has had three names. Why might a place change its name?
Try at home or in class
- Build a fortress on a tray from clay or sand, with pointed bastions at the corners, then pour water around it to make islands.
- Draw a fortress wall with straight corners and one with pointed bastions, and compare the shapes.
Key vocabulary: fortress, bastion, rampart, dry dock, district, beacon
Where these facts come from
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Fortress of Suomenlinna (World Heritage List) , UNESCO World Heritage Centre
- History of the Fortress , The Governing Body of Suomenlinna (official website)
- File:Suomenlinna.jpg , Wikimedia Commons
- UNESCO World Heritage List , UNESCO World Heritage Centre (Linked as a reference; site facts come from Wikidata)
- Wikimedia Commons , Wikimedia Foundation (Per file (public domain, CC0, CC BY or CC BY-SA); see each media record)
Checked, not yet human-reviewed. Last updated November 1, 2026. Spotted a mistake? Tell us.