Polish fortifications built in 1939 in the region of Bielsko were part of a defensive system, which had a length of about 10 km and was located in the area of the stream valleys of the Wapienica and Iłownica and the Klimczok massif. The fortifications protected the city from the west and north, and were one of the largest networks of the Polish positions in that time. They were constructed in the spring and summer of 1939. 21 shelters, which were then built, have been preserved until today.