A periscope tube with remains of the mechanism to rise/lower the periscope. Most of the pillboxes, except for the smallest ones, were equipped with good quality periscopes mounted in a metal tube which was closed by a round plate at the roof of the structure. The plate was moved sideways by a long iron rod attached to the handle shown at the photo. Then, a periscope could be risen to provide 360 degrees view. Those plates and tubes proved to be the weakest spot of the Soviet bunkers. The round plate (or lid) could be pried open by a crowbar and grenades could be rammed inside the tube. Most often than not, once the German assault pioneers got to the roof it was usually beginning of the end for the crew inside.
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