Instruction on the Fortification of Cities

Here is a translation of the provided German text, following all instructions:

Here is a diagram of the underground area with all its contents, such as the doors, corridors, staircases, vaults, and streichweren defensive works. All diligently recorded and measured according to its writing with the small schůch shoe, i.e., unit of measurement.

This architectural ground plan depicts a semi-circular defensive structure or bastion, labeled as the "vnder grundt" basement or foundation level. The plan is intricate, showing internal rooms, vaulted ceilings marked with small crosses, staircases ("Stiegen"), and corridors ("Geng"). The left half of the structure is filled with dark cross-hatching, while the right half illustrates the masonry patterns of the stone walls. Reference letters (h, l, f, m, k, s) are placed around the outer perimeter of the diagram.