File:Shlisselburg Fortress. Шлиссельбургская крепость. Nöteborg (10025066323).jpg

The first fortification was built by Swedes in 1299 but was lost to the Novgorodians in 1301. A wooden fortress named Oreshek (also Orekhov) ("Nutlet") was built by Grand Prince Yury of Moscow (in his capacity as Prince of Novgorod) on behalf of the Novgorod Republic in 1323. It guarded the northern approaches to Novgorod and access to the Baltic Sea. The fortress is situated on Orekhovets Island, whose name, refers to nuts in Swedish and (Pähkinäsaari, "Nut Island") in Finnish and Russian. After a series of conflicts, a peace treaty, was signed at Oreshek on August 12, 1323, between Sweden and Grand Prince Yury and the Novgorod Republic which was the first agreement on the border between Eastern and Western Christianity running through present-day Finland. A modern stone monument to the north of the Church of St. John in the fortress commemorates the treaty. Twenty-five years later, King Magnus Eriksson attacked and briefly took the fortress during his crusade in the region (1348–1352). It was largely ruined by the time the Novgorodians retook the fortress in 1351. The fortress was rebuilt in stone in 1352 by Archbishop Vasilii Kalika of Novgorod (1330–1352), who, according to the Novgorod First Chronicle, was sent by the Novgorodians after several Russian and Lithuanian princes ignored the city's pleas to help them rebuild and defend the fort.[5] The remnants of the walls of 1352 were excavated in 1969 and can be seen just north of the Church of St. John in the center of the present fortress. The fort was captured by Sweden in 1611 during the Ingrian War. As part of the Swedish Empire, the fortress was known as Nöteborg ("Nut-fortress") in Swedish or Pähkinälinna in Finnish, and became the center of the north-Ingrian Nöteborg county (slottslän).

In 1702, during the Great Northern War, the fortress was taken by Russians under Peter the Great in an amphibious assault: 250 Swedish soldiers defended the fort for 10 days before they surrendered. The Russian losses were 6000 men against 110 Swedish losses. It was then given its current name, Shlisselburg, a transcription of Schlüsselburg. The name, meaning "Key-fortress" in German, refers to Peter's perception of the fortress as the "key to Ingria". During the times of Imperial Russia, the fortress was used as a notorious political prison; among its famous prisoners were Wilhelm Küchelbecker, Mikhail Bakunin and, for 38 years, Walerian Łukasiński. Ivan VI of Russia was murdered in the fortress in 1764, and Lenin's brother, Aleksandr Ulyanov, was hanged there as well.