The tree which got hollow is still under the government's protection. It is a source of study in the maximum life span of gingko in Korea. On the basin of the Taedong River centred on Pyongyang, there are 14,000 dolmens in particular. Dolmen which is symbolic of the ancient monument represents the resourcefulness and talent of the Korean people who have created brilliant culture since ancient times. The Korean dolmens are classified into three types according to the names of places where they were discovered-chimchon, odok and mukbang.
Every chamber has a thin flat stone set on four edgewise sides.
Their top is covered with a stone roof and the chambers are supported by stone piles. This shows that the Korean dolmen developed from a simple structure into a sophisticated and refined one. These three types of dolmen representing every stage of dolmen development are found concentrically on the basin of the Taedong River centred on Pyongyang. This shows that dolmen structure finds its cradle and centre on the basin of the river with Pyongyang at its centre, like every other aspect of the culture of ancient Korea. It provides clear evidence that Pyongyang was the capital of ancient Korea which existed for nearly 3,000 years in the east, with a fine history and cultural tradition, and the cradle of the Korean nation.