Situated in Tay Giai and Xuan Giai hamlets, Vinh Tien Commune and Dong Mon hamlet, Vinh Long commune, Vinh Loc district, in the central province of Thanh Hoa, the citadel was built by Ho Quy Ly when he was a mandarin under the Tran Dynasty as he planned to move the capital city from Thang Long (now Hanoi) to Thanh Hoa.

Because of this, the citadel was very carefully built.

With its position, which is not easy to approach from the surrounding areas, the citadel was regarded in the old days as a bulwark against invading enemy.

The citadel, almost square-shaped in design and made from large blocks of stone, sits on a site of about 770,000m2. Its principal gate faces Southeast (often referred as South). The Southern and Northern walls measure 877.1m and 977m while the Eastern wall is 879.3m and the Western wall is 880m.

Tay Do citadel has four main gates, the South, North, East and West. The roads cross the South-North axis and the East-West axis with the junction right in the middle of the citadel.

Outside the citadel, the roads continue to four major directions. According to the recent archeological research, the North road leads to the old Nam Giao place of worship on Don Son mountain.

The citadel consists of walls, gates, a ditch and artificial springs and wells, but due to weather conditions and war damage only its stone walls and gates remain in good condition.

The stone walls measure 5-6m in average. The South gate, it is nearly 10m high and the walls are 4-5m wide, sloping slightly inside the citadel.

The walls, made from blocks of stones without using cement, weigh about 15-20 tonnes each.

All the four main gates are in the shape of arches. The South gate is the biggest and the North gate shares the same architectural design but is a little smaller. The East and the West gates are the smallest but look similar.

Despite being the capital city in a very short time, its interior has been completely destroyed, the remains are strong and undeniable proof of the people’s abilities and skills. Historical materials records an amazing short construction time of only 3 months. Until now, it is still a great mystery how King Ho Quy Ly and his people could move and erect such an enormous amount of stones in such a short of time.

Vietnamese feudalism is closely attached with the country’s forts and citadels, but there is only one Tay Do stone citadel with its unique design. Scientists also recognise that it is the largest, most original and only remaining citadel in Southeast Asia as well as being very rare one in the world.

Recognised as the national historical site in 1962, the citadel was soon to be forgotten and even damaged further. Fortunately, in late November 2006, the central province Thanh Hoa established a steering committee to create a profile for the Tay Do citadel as world cultural heritage. The work was assigned to the Thanh Hoa Provincial Department of Culture and Information. The province also carried out some essential work to preserve the citadel.

The profile of the Tay Do stone citadel was submitted to UNESCO for consideration on September 29, 2009.