- Regelbau 603 -
The Regelbau program was a project by Germany in the second world war. It was a series of standardized bunkers designed to be built in large numbers in the Siegfried line and the Atlantic Wall. There were multiple strength levels at which these bunkers could be built, with the 603 being level B (2.0 meter thick walls) and being primarily designed for the army(Heere). The 603 was a "Unterstellraum für 2 Kampfwagen, Zweigeschossig", or bunker for storage of 2 fighting vehicles, with 2 floors. It also had crew quarters on a underground floor, with enough room for 6 men.

- Schematic -
The schematic itself is made in Minecraft 1.16.5, and is shown in the more detailed map (map). The images in the superflat world are made in 1.7.10, but this version doesn't have "clean" stone stairs and slabs. You can solve this problem with some mods like Staircraft and Slabcraft. The Tiger, Tiger II and Panzer IV are from this McHeli content pack:
McHeli mod
McHeli German WW2 content pack

If you have any tips don't hesitate to tell me in the comments!