@oosidhuo: Tianmen Mountain in Zhangjiajie features a massive underground escalator system within its tourism tunnel, comprising 16 interconnected sections and a total of 40 escalators (some sources say 19 in phase one), making it the world's longest mountain tunnel escalator, allowing visitors to ascend the mountain and reach the famous Tianmen Cave (Heaven's Gate) with ease, avoiding the 999 steps. #zhangjiajie