Patarei Sea Fortress

Patarei Prison, also known as Patarei Sea Fortress and Tallinn Central Prison, commonly known as The Battery, is a building complex in Kalamaja district of Tallinn, Estonia. The premises cover approximately four hectares of a former sea fortress and prison, located on the shore of Tallinn Bay.The fort was built from 1830–1837 as part of the fortifications for the tsarist Russian state. The building order was given by emperor Nicholas I. In 1864, Tallinn was removed from Russian Empire’s list of fortresses due to Russia’s defeat in the Crimean War, and the fort was converted into barracks.

The Republic of Estonia, which declared independence in 1918, reconstructed it as a prison after World War I. In 1919, the fort's main function became a prison, lasting until 2005.

Source: Wikipedia