Comrade! It's practically nearby (see the map)...
Listen, comrade, and remember: the main defensive line of KaUR includes 10 BDR - from Sestroretsky in the west, to Nikulyassky in the east. In the rear zone there are 5 BDR. The most accessible structures are in Sestroretsky, Beloostrovsky, Lembolovsky and Elizavetinsky BDRs. I could recommend the two-kilometer scale map 'Karelian Isthmus - 1938-2001'. History and Modernity' (cost 35 rubles), where most of the KaUR structures (and not only...) are depicted.
I won’t describe in detail what and where I’m doing for you, comrade, because it’s much more pleasant to find your way around on your own, with a compass in your hands, a map in your teeth, and with sparkling eyes and a trusty revolver in your belt, to discover mysterious structures lost in forests and swamps...