This is a well called Hoguknyongbyeoneojeong in the Silla period.
The upper part of the well above the ground is 70cm tall and octagonal.
The lower part of the well is cylindrical.
This structure represents the essence of Buddhism.
According to Samgukyusa, emissaries from Tang China visited Silla in 795, the 11th year of Silla King Wonseong.
They changed three dragons for protecting the country into small fish, and took them to China.
The next day, two women came to the king and identified themselves as the two dragons' wives living in Dongji pond and Cheongji pond.
They asked the king to retrieve a dragon in the Bunhwangsa well and their husbands whom the Chinese emissaries took them in a bamboo.
The king immediately sent his men to bring back the dragons, and let them live in the well.