Fort Kronshlot is one of the key pieces in the chain of sea defences that made Kronstadt so important to Saint Petersburg. Built under Peter the Great on an artificial island in the Gulf of Finland, it helped close the naval approaches to the new imperial capital.
For travellers, the fort is less about polished interiors than about geography. Seeing it from the water or from Kronstadt's shores makes the whole city make sense: this was not just a naval town, but a fortified gate set between the Baltic and the Russian capital.