The second-class fortresses are Kronstadt and Sveaborg in the Gulf of Finland, Ivangorod in Poland, Libau on the Baltic Sea, Kerch on the Black Sea and Vladivostok on the Pacific. In the third class are Viborg in Finland, Ossovets and Ust Dvinsk (or Dunamunde) in Lithuania, Sevastopol and Ochakov on the Black Sea, and Kars and Batum in Caucasia.
IVANGOROD, a fortified town of Russian Poland, in the government of Lublin, 64 m.
A branch line, parallel to this last, connects Skierniewice with Thorn and Bromberg; while a military railway connects the fortresses of Warsaw and Ivangorod with Brest-Litovsk, via.
The centre of these latter is Warsaw, with Novogeorgievsk, formerly Modlin, in the north, at the mouth of the Bug, and Ivangorod, formerly Demblin, in the south, at the mouth of the Wieprz.
Since that time the Russians have made many additions to the works, and the place now forms, with Warsaw, Ivangorod and Brest-Litovsk, the so-called Polish Quadrilateral.