The Hanoitimes - A lot of mystery lies beneath the grounds of the Ho Dynasty Citadel in the north-central province of Thanh Hoa, said Tong Trung Tin, associate professor, doctor and head of the Institute of Archaeology in Hanoi.

Dr. Tin said that besides the Nam Giao worship platform which was discovered last, most of the grounds around Ho Dynasty Citadel have not been excavated. Archaeologists have o­nly dug up across 20 hectares of the citadel complex.

The Ho Dynasty Citadel is located in a thinly populated area, still unaffected by industrial development. Thus the site is almost intact.

According to historical references, the citadel was built within a three month period. However Dr. Tin believes it is impossible to transport and pile thousands of stone blocks to build the huge stone walls during such a brief time. This process takes at least o­ne year even with advanced technology.

Scientists have researched and uncovered that ancient stones used for construction of the citadel were taken from the An Ton Mountain, located close to the citadel. They found pottery and tile pieces buried around the mountain quarry site to prove this.

Mystery surrounds how 10-26 tons of stone blocks could be transported from the mountain to the citadel site. Unfortunately, most of the documents relating to the Ho Dynasty Citadel were lost during the previous wars.

On June 16, Thanh Hoa Province received the UNESCO certificate recognizing Ho Dynasty Citadel as a World Cultural Heritage Site.