Nestled in southeast China's mountainous area in Fujian Province, a multi-story mud housing complex that has weathered over 600 years is still in use.

Nanjing County has the biggest concentration of such earthen houses, with more than 20,000 of them occupied by locals. The Tianluokeng buildings, seated on a mountainside 70 km from the county's downtown center, is a typical example.

Some 500 people -- all surnamed Huang -- make up the 105 households in the village. The families live in five three-story buildings grouped closely together. Each floor of the five buildings is connected by a corridor.

Villager Huang Guolang has completed a genealogy of the Huang clan which suggests that they are the offsprings of Huang Chao, a peasant who rose up against the imperial rule of the Tang Dynasty (618-907). The 56th grandson of the rebel moved his family to the reclusive place during the Qing Dynasty when it was ruled by Emperor Kangxi (17th Century).

The man said that they are the 23rd generation to live in the mud village.

Chinese archeologists who have inspected the site said that the circular arrangement of the mud houses reflects the traditional Chinese notion of harmony. The multiple floors were designed to separate the living spaces from the household workshops. The most intriguing feature of the architecture, however, is that the mud is a blend of soil, sticky rice, brown sugar and lime, and is as solid as rock.

Villagers said it usually takes up to a dozen years to construct a building like this, because the gooey mud blend is reinforced with bamboo poles, log cabin-style, and has to be formed layer by layer to allow the mud to dry naturally.

The Huang families use the first floors as kitchens and utility rooms, the second for storage and the third as bedrooms.

An inspection group composed of experts from the United States and Australia said that they were deeply impressed with the unique architecture.

After conducting an in-depth study of the building process, building materials, design, geographical surroundings, engraved designs on the wall, and fire- and water-proofing systems in the structures, the group agreed that the complex is worthy of being included on the World Heritage List of historical buildings.

Officials in Nanjing County said the application process for the prestigious list is underway.