Introduction to Tianjing and Tsutenkaku: There is an island in the center of Nanhu Lake, and there is a well on the island. The water in the well is more than two meters above the lake surface all year round. When the lake water rises, the well water does not rise, and when the lake water falls, the well water does not fall. It is a wonder. , it can be said that "the water in the well does not interfere with the water in the river". It is said that the water in the patio comes from the sky for passing gods to take a break and drink tea, hence the name "Patio". Later generations built a pavilion on the well to protect it, which was named "Tongtian Pavilion".