Sveaborg, also known as Suomenlinna, is a system of bastion fortifications on islands near Helsinki, the capital of Finland. Administratively, it is part of the city of Helsinki. From the 18th century until the mid-20th century, the fortress defended Helsingfors from the sea, and since the 1960s, it has become a museum and residential area.

The Swedish government decided to strengthen the Wolf Archipelago after the Russo-Swedish War of 1741-1743 and the signing of the Treaty of Åbo. In 1746, the leadership of the fortification works was entrusted to Major Augustin Ehrensvärd, assisted by architect Tunberg.

In 1756, Ehrensvärd initiated the reorganization of the Swedish galley fleet, which became known as the army fleet, with Sveaborg as its main base. That same year, Ehrensvärd was promoted to the rank of major general. In 1748 and 1758, the current Kustaanmiekka was built, and all works were completed in 1770, costing 25 million riksdaler.

In 1808, during the Russo-Swedish War, the fortress was besieged by the Russians and surrendered on April 26 after a short siege. The Russians captured 7,500 prisoners, over 2,000 cannons, significant supplies, and 110 warships. The commandant of the fortress became Russian General Mikhail Leontievich Bulatov.

In 1809, Finland became part of the Russian Empire, and Sveaborg remained a Russian fortress, retaining its previous name. In 1811, the future famous critic was born into the family of military doctor Belinsky. In 1826-1827, the Decembrist Mikhail Lunin was held in the fortress prison.

On July 1, 1835, Major General Alexander Vasilyevich Yakovlev became the commandant of the fortress, who received numerous awards and commendations from the commanders of the Finnish Corps and the troops in Finland for his care of the lower ranks and diligence.

In 1855, during the Crimean War, Sveaborg was bombarded by the Anglo-French fleet. On August 9, intense shelling began, lasting for two days. The squadron left, losing several ships and causing minor damage to the fortress. The garrison lost 44 killed and 110 wounded lower ranks, as well as several officers.

After the war, the fortress was reconstructed, new fortifications and artillery positions were built, and more modern guns were installed.

In the early 20th century, about 1,500 people lived in Sveaborg, not counting the garrison. In summer, communication with Helsingfors was maintained by small steamers. The fortress housed a station of the Russian Navy, docks, arsenals, a sailors' school, barracks, powder magazines, freshwater reservoirs, and an Orthodox church that was rebuilt. The Sveaborg Uprising occurred in 1906.

During World War I, a chain of defensive structures was built around Helsingfors, partially located on the islands. The purpose of the fortress was to ensure the safety of the Baltic Fleet's naval base, protect Helsingfors, and guard the approaches to Petrograd from possible German invasion.

The old fortress no longer provided adequate protection, so the main defensive line was moved beyond its limits. New coastal artillery batteries were built on remote islands, and fortified lines around Helsingfors were intended to stop land attacks. The Sveaborg fortress was unfinished in 1917 when, due to the February Revolution, most work was halted. Some work continued throughout 1917, but after the October Revolution, construction stopped completely.