Infantry casemate bunker concrete fortress “O3/23/A-160 Z” řopík near Velké Březno, Czechia https://www.ropiky.net/dbase_objekt.php?id=1075725593
Map: https://goo.gl/maps/6kvGAnSVkM2Yb7gC6
https://en.wikipedia.org/wiki/Czechoslovak_border_fortifications
Former part of Czechoslovak border fortification built in 1930’s, now under heritage protection. http://www.fortif.net/files/overview.php
Photogrammetry scan (350x24MP DSLR + drone by https://sketchfab.com/kubacpetr )