Oka River to Kozelsk, and was built by Ivan the Terrible. The next one, built a while later, followed the line Alatyr - Orel - Novgorod Seversky - Putivl. Feodor I of Russia had built the abatis on the line Livny - Kursk - Voronezh - Belgorod. Simbirsk line was constructed about 1640, and continued the Belgorod line from Tambov to Simbirsk on the Volga River. In 1730-31 the Kama line separated Kazan from the Bashkirs. From about 1736 a Samara-Orenburg line closed in the Baskirs from the south. See also Great Wall of China Atlantic Wall References External links Recent photos from one of the regions of the Abatis Border Recent photos of the Simbirsk line Photos from the Zakamskaya line Photo 1024x768 (Kolomna Kremlin) Photo 1024x768 (Kolomna Kremlin, Pyatnitskie Gate) Fortifications in Russia Tsardom of Russia Fortification lines