slovenian springs near izborsk fortress, pskov region, russia

apart attack baltic barbican border both brother built burial canals cannons center centuries chronicle compatible constructed decisive designed development east entrances estonian fortress from gorodishchenskoye governance importance izborsk krivich lands larger lithuanian maximum medieval meters military most mound nikolski now occasional oprichnina portcullis prone pskov range regiment region reinforcement republic rest rivers role route rurik russia russian serving shown side slavic slavonic small still strengthening system thickened thicker tourist tower towers trade truvor western wide