Overview of the Cu Chi Tunnels Structure As you can see in the illustration, this underground city was built manually over 20 years, stretching for more than 250 kilometers. It features a three-level structure designed to withstand heavy attacks. Level 1 is about 3 meters deep, strong enough to protect against small bombs and artillery shells. Level 2 lies 6 meters deep and could withstand heavy bombs. Level 3, at a depth of 12 meters, was the most secure level, offering protection even from large bombs. The tunnels played a crucial role in the 1968 Tet Offensive, allowing our soldiers to secretly approach and launch a surprise attack on Saigon. Combat Tactics and Traps The tunnel system was a weapon in itself. Let's look at the picture to understand how. On the ground: Our soldiers used cleverly camouflaged trenches, or "spider holes," to hide and launch surprise attacks before quickly retreating to the safety of the tunnels. To counter the enemy's use of scout dogs, our soldiers even wore captured U.S. uniforms to confuse their sense of smell. Most of the dogs that entered the tunnels were caught in pre-set spike traps. Underground: Once inside, enemy soldiers were met with a series of ingenious traps. You can see the sharp bamboo spike traps, landmines, and even traps with venomous snakes or scorpions. The tunnels' winding, zig-zag design prevented U.S. soldiers from seeing or shooting straight down the passages. When the enemy used poison gas, our soldiers devised water pits to block the air, allowing them to hold their breath and pass through. Every part of the tunnel system was a testament to meticulous planning and ingenuity. Life and Logistics Underground The tunnels were not only a place for combat but also a place for life. The Hoang Cam Kitchen: Please look at the image of this special kitchen. It was designed so that smoke from cooking was channeled through long, winding underground flues before being released discreetly through the bushes a safe distance away. The enemy could never detect it. Medical and recreational facilities: Deep within the tunnels, you can see a field hospital for treating the wounded and even a small propaganda cinema to boost morale. Innovation and self-sufficiency: In the weapons workshop, engineers repurposed unexploded U.S. bombs and other discarded materials into mines and grenades. They even turned a bicycle into a generator to power the hospital and workshop. Water source: Finally, you can see the deep water well, which provided a clean water source, protected from the chemical defoliants the U.S. forces sprayed on the surface. All of these features combined to create an entire "underground city"—a place for both fighting and living, demonstrating the extraordinary resilience and creativity of the Vietnamese people during the war.