1748
The construction of the fortress was commenced under Artillery Officer Augustin Ehrensvärd, assisted by Chief Inspector Carl Hårleman and Captain Bengt Gabriel von Spången. Two years later the fortress was named Sveaborg, or Viapori in Finnish.
1772
After Ehrensvärd's death, Lieutenant General Jakob Magnus Sprengtporten was assigned to supervise the construction; he was followed by Captain Nils Mannerskrantz.
1808
Viapori surrendered to the Russian army almost without a fight. During the Swedish period, the main parts of the fortress had been completed.
1809
Finland became part of the Russian empire. The development of weapons and the change in direction of defense brought new additions to the fortress. Viapori became a community with urban features, cathedral and pubs included.
1855
This year saw the Crimean War and the bombing of Viapori. A large English-French fleet bombed the fortress but did not attempt a seizure. Buildings were damaged and only a few would be restored.
1917
When Finland became independent, the fortress was given to the Finnish Defense Forces and renamed Suomenlinna. Kustaanmiekka and Susisaari soon became museum areas. Only a few new buildings were constructed: an industrial hall at the dock, and the elementary school.
1973
Suomenlinna was transferred from the Defense Forces to the Governing Body of Suomenlinna.
1974
A practical plan for Suomenlinna was approved, the idea of which was to create an active community in the fortress.
1991
Suomenlinna was admitted to the list of Unesco World Heritage sites.
1998
The island fortress celebrates its 250th anniversary.