Travelers often traveled to Yunomine to take hot spring baths before continuing on to Kumano Hongu Grand Shrine. Nestled among the mountains in a small valley, Yunomine Onsen is the oldest known hot spring in Japan. It was established in 113 A.D. by Emperor Seimu. It has been well-known since the Nara (710-794) and Heian (794-1185) eras, and it is also famous as a spa for curing illnesses from the story of Oguri Hangan. It is sometimes called a "spa for giving people blessings of children." Tsubo-yu, a hot spring (yu) that looks like a giant clay pot (tsubo), is the first hot spring registered as a world heritage site. Boiling eggs in the hot spring water is popular with travelers, and eggs are sold ready to lower into the boiling hot water.