Lin Feng frowned. 'Is the Zerg Race's plan to attack from underground?'
But he had watched this outpost bunker being built. To prevent the Zerg Race from tunneling through, not only was the foundation deepened, but the ground was also paved with a layer of reinforced concrete nearly two meters thick.
The materials were all readily available from the cement factories of the two cities. Due to the rapid decline of the real estate market in recent years, there was a massive surplus of inventory with a short shelf life. It made more sense to use them here than to transport steel and grain back to the rear.
So, they used local materials...
And that was how the engineering marvel of the Wu City defense line was created.
A two-meter-thick surface defense layer would take a Red-Armored Beetle more than half a month to dig through. Even if a Tiger Spine Zerg took on the task itself, it would still need over ten days just to scrape out a hole.
