Machine-gun embrasure

Origin of this loophole is peculiar. There are no MG embrasures in the construction project of the bunker. But during WW2 Finnish shell hit the bunker and made a considerable crater on it's wall. After the war in 1950 the embrasure for 7.62 Maxim MG has been made here.
PS: First in Russia bunker museum was established in this installation recently. I'll tell about it soon...