Introduction to the mountain gate: The west gate is the earliest mountain gate of Laojun Cave. It was built in the ninth year of Wanli in the Ming Dynasty, more than 400 years ago. There is a "Tai Chi Palace" door on it, with a Tai Chi diagram surrounded by eight trigrams, implying the evolution of the universe and the mystery of Tao. "Zifu" and "Dantai" are engraved on the left and right sides, symbolizing that Laojun Cave is a fairy cave.