The remains of a public toilet with an advanced purification facility, presumed to be built about 150 years ago, were discovered at a Joseon Dynasty (1392-1910) palace in Seoul, a government agency said Thursday.

The toilet ruins, which have the form of a rectangular stone pit measuring 10.4 meters in length, 1.4 meters in width and 1.8 meters in height, were uncovered at Gyeongbok Palace in the heart of the capital, according to the Ganghwa National Research Institute of Cultural Heritage.

The remains were unearthed in an area south of the crown prince's residence, called Donggung, of Gyeongbok Palace, the first and largest of Joseon's royal palaces, the agency said.

It is the first time that toilet remains have been discovered inside a Joseon Dynasty palace.

The institute assumed that the public toilet was built in 1868 and used by around 150 low-ranking officials, court ladies and soldiers guarding the palace for about 20 years. It explained that several Joseon documents and palace maps, as well as the discovery of parasite eggs and cucumber, eggplant and perilla seeds from the soil, indicate the remains were a toilet.

The institute noted that traces of a purification facility similar to a modern septic tank were found at the ruins, and both the floor and walls seemed finished with stone to prevent excrement from leaking out.

But the institute said it has failed to find how water got into the toilet remains due to damage at the entrance.

"A large palace toilet with a purification facility was unprecedented 150 years ago. It is meaningful in that our country's unique and excellent technology was applied," said an institute official. (Yonhap)