Guilin is a world famous city with numerous limestone hills and caves. According to geologists, Guilin was originally on the ocean floor about 300 million years ago. About 200 million years ago, a lot of limestone deposits were located on the bed of the ocean.Due to the movement of the earth’s crust, the seabed rose and became dry land. With the erosion caused by rainwater and underground water, all the limestone hills, caves and rivers were formed as the karst formation during this period of time in Guilin. When visiting Guilin, the numerous fantastic caves are a great highlight that one should not miss. Among all the caves, the best ones to visit are the Reed Flute Cave, Crown Cave.