Well, a Great Wall is a solid line of stone, but a bunker is a damn good piece of engineering – both can hold off a lot. Against a medieval sally, you’d rely on the wall’s height and the fact that a siege engine can’t get past it if it’s built right. But you’d also need archers or catapults to bring the attackers down before they even get close. A bunker, on the other hand, gives you air filtration, water, and a fortified door, so the medieval troops would have to dig tunnels or take the roof, and that’s slow, expensive, and you’re still exposed to fire from above. Against a post‑nuclear horde, the Great Wall is a no‑go – it’s just concrete and stone, and you’re still breathing a toxic atmosphere. The bunker shines here: you can seal it, vent, and stock up on rad‑tolerant food. But if the horde breaks through the door, you’ll have to use your weapons and a solid exit strategy. So, in short, a bunker wins the long‑term siege, while the Great Wall might hold a medieval army if you’re clever with siege weapons. Both need supplies, good exits, and a plan – that’s the key.

You’re right – the wall’s sheer presence could choke a legion’s nerves, while a bunker is all about keeping the air clean. Both are products of what they had to fight: stone to block armies, concrete to seal out radiation. In either case you’re only as strong as your supplies and your exits.