Jiuqudong Introduction: The Jiuqudong Tunnel is 1,220 meters long and is the longest tunnel on the Zhongheng Highway. The Jiuqudong Trail is the most essential section of the Taroko Gorge. The trail is close to the mountains and deep ravines. Looking down, you can see the rapid Liwu River. The mountain walls on both sides are close to each other. The uncanny workmanship and steep terrain are breathtaking. The simple tunnels and mountain walls along the way still retain the chisel marks left by the drills used when the Zhongheng Highway was excavated. In addition, the gold mining road dug by the Japanese in the early years to mine placer gold in Liwu River can still be clearly seen with the narrow traces hanging on the rock wall outside the trail.