According to old books including "Chronicles of the Feudal Joson Dynasty" and "Tonguibogam" (Encyclopedia of Traditional Medicine of Korea), Korean ancestors had a good grasp of pharmacological effectiveness of hot springs and used them for treating diseases.

It is well evidenced by remains of the Kalsan Hot Spring Bath House in Kudang-ri, Phangyo County, Kangwon Province.

The hot spring is radon spring and efficacious for skin disease, neuralgia, chronic gastritis, arthritis, etc.

The remains of its bath house consist of building site and four water tanks.

Seen at the building site are cornerstones and platform stones made of granite, and two sets of water tanks in the east and west.

Each water tank is connected by gravity-fed waterway made of semicircular granite.

"Sejong Sillok" (Chronicles of King Sejong) (1419-1450) wrote that King Sejong had a cure at the Kalsan Hot Spring Bath House.

There is a site of temporary palace scores of meters northeast away from the remains of the hot spring bath house.

The historical facts go to prove that the remains of the Kalsan Hot Spring Bath House are 570-odd years old.

Now, the Kalsan Hot Spring Sanatorium stands near the remains.