Northern Forts is the circuit of 9 artillery forts. This forts are the sea artillery installations on the artificial islands which were built for protection of northern fairway to St.Petersburg. Distances between them are near to 2-2.5 kms for continuous gun's fire zone and convenient ammunition supply of forts by water.

 
First fortification plane of the fairway was made in Peter Great times. However the works began in 1800th. The continuous pile and wooden frames filled with boulders and earth barrier were arranged and two wooden artillery batteries on the piles were constructed also.

 
In 1824 forts were fairly destroyed by the strongest flooding. In 1827 was made decision to replace wooden strengthening by stone ones. Just before the Crimean war stone casemates were constructed. It's brick vaults has thickness in the lock near to 2 meters, all forts were reverted with a granite. In June, 1854 the England-French sea squadron has approached near to Kronstadt. They sow to the forts and batteries, lost a pair of ships on mine obstacles (first-ever used here) and got out with anything. The same repeated in 1855-56

 
1941 - WWII. German bomber's pilots has gloomy memoirs about anti-aircraft artillery of Kronstadt and its forts. They wrote that artillery and machine-guns were setting out in all possible places. Observation posts, artillery positions and concrete machine-gun pillboxes are well preserved on the forts from that times.