According to the history, there was a wall with gates surrounding the Thang Long Royal Citadel. They were under strict supervision, open during the day and closed at night. There were orginially 16 gates in the 18th century, but only five of them remained by the early 20th century.
A picture of O Quan Chuong in the past (VOV)
Today, only the Quan Chuong Gate is still standing. Built in 1749 but has been restored many times over, the gate has typical architecture of the Nguyen Dynasty. It consists of two levels; the lower level has three arched doorways and the upper level is covered by 4 roofs.
As the only original gateway to the Old Quarter that is still standing, it is considered as a page of history of Ha Noi. In 1994, the gate was officially recognized as a historic relic site. In 2010, it was restored once again with a project funded by the US Ambassadors Fund for Cultural Preservation.