SCHLÜSSELBURG, a town of European Russia, in the government and 21 miles E. of St Petersburg, at the point where the Neva issues from Lake Ladoga. It is partly built on an island, on which stands an old fortress, frequently used as a state-prison. The town is chiefly built of wood, and has manufactures of chintz and calico, and some trade with St Petersburg. Pop. 4000.