Introduction to Tianmen Stone: On the west bank of the river, there is a large bluestone about 20 meters high, 10 meters wide and 2 feet thick. People call it "Tianmen Stone". It splits 1 foot straight from the cliff behind it. If you have more than enough, it seems to be about to collapse, and it is extremely dangerous. As long as you exert a little strength, it will collapse and cause the river to block.