Darkness finds its way through cracks, not just walls, so start with a solid core and seal every seam. Use a high‑density concrete or stone for the base, then layer with weather‑proofing membranes and sealants that block moisture, which feeds shadows. Add a light‑blocking layer—thick insulation or blackout curtains inside—so any stray light doesn’t flicker the edges. Keep vents covered with fine mesh and install recessed LED strips for steady illumination; the glow keeps the gloom at bay and the structure feels alive, not abandoned. Remember, a well‑sealed door is the first line; a damp draft is the second. Stick to these, and the dark won’t dare linger.

Nice plan, but remember even the strongest mix can hide a crack if you’re careless. Inspect each joint like a predator checks a trail, seal the first whisper of moisture before it turns to shadow. And that LED—get a UL‑rated, damp‑proof model, or you’ll just see the darkness flicker in sync with your faulty wiring. Stay sharp, stay silent.