A number of ancient artifacts have been found in a cave under Ru Than Mountain in Thanh Hoa Province, some 3.5 kilometres Southeast from the Ho Citadel.

Vases, jars, bowls, plates, pots and other artifacts made from terracotta and ceramics were discovered in a 20-square-metre cave, which had been covered over by layers of rocks. There was also a big jar containing a variety of coins and a sword. Human bones were also found at the site.

The cave has two levels in two floors with numerous paths leading to smaller caves.

There were signs that the cave served as some sort of residence. There were seats and even a kitchen, all fashioned out of rock. According to local legend, the place might have once been used by people trying to escape violence during wartime. Other stories say that it was occupied by the workers who built the Ho Citadel.

According to archaeologist Vu The Long, the artifacts did not originate in Vietnam and were made around the 15th century, the time of the Ho Dynasty.

Ho Citadel is located in Vinh Loc District, Thanh Hoa Province. It was the capital of Vietnam from 1397 to 1407. The citadel was constructed between 1397 and 1401, with some modifications done in 1403.

The Ho Citadel was recognised as a UNESCO World Cultural Heritage Site in June.

Some photos of the relics:

The narrow door to the cave

The cave is quite large

Stone seats arranged on the floor

Terracotta and ceramic jars, bowls and pots

Kitchen

Bone fragments