Introduction to Yuetang: Common people call it Yuetang, which is the so-called "cow belly". It was built during the Yongle period of the Ming Dynasty (1403-1424 AD). The Moon Pond is in the shape of a half-moon and is green all year round. The surface of the pond is as level as a mirror. Bluestones are spread around the pond and marsh, and the pink walls and blue tiles are arranged neatly and orderly on all sides.