In 1805 the ancient northern citadel was rebuilt according to Vauban principles, on a smaller scale than before, with five gates, none of which faced south. In 1831 Gia Long's son Minh Mạng (1820-1840) once more changed the name of the city, this time to Hà Nội ('city within two rivers') and in 1848 Tự Đức (1847-1883) further reduced its importance by ordering the destruction of most of its royal palaces and the removal of many articles of value to Huế. Following the colonial conquest, the French symbolically took over the citadel, destroying most of the remaining buildings and replacing them with military barracks and depots. Thereafter it served as the headquarters of the People's Army (and latterly of the Ministry of Defence) until 2004, but in that year the Ministry of Defence began transferring the entire 49,135 square kilometre site to the Hà Nội People's Committee with a view to permitting necessary archaeological work and finally opening up most of the citadel to the public as a tourist attraction before the Hà Nội 1,000 celebrations in 2010. Responsibility for managing the site as a visitor attraction has since been passed to the Hà Nội Service of Culture and Information.

At the time of writing visitors entering through the Đoan Môn (main gate) can tour the Điện Kính Thiên (Kính Thiên Palace), the 'D67' war room and underground bunker of General Võ Nguyên Giáp and a number of other areas of the old citadel - with the exception of the Điện Hậu Lâu (Princess's Palace) and the Bắc Môn (north gate), which have their own separate entrances (see addresses above). The citadel flag tower (Cột cờ Hà Nội) can be viewed when visiting the nearby Việt Nam Military History Museum.

In 2003 work to lay the foundations of a new National Assembly building at a 21,400 square metre site to the west of the 18th century citadel perimeter was halted when excavations led to the largest and most spectacular archaeological find in Việt Nam's history - foundations of ancient royal palaces, including one structure 1,000 square metres in size, a drainage system, wells and traces of an ancient river and lake, plus tens of thousands of artifacts, many dating back to the first millennium CE and most in an excellent state of preservation. Given the significance of this find, it was quickly decided to relocate the new National Assembly of Việt Nam building to an alternative site near the Mỹ Đình National Stadium. An exhibition of many of the most important artefacts uncovered at the site was subsequently toured around the country and many of these artefacts are now on view in the restored Điện Kính Thiên (Kính Thiên Palace). Since that time the Ministry of Culture, Sports and Tourism has sought UNESCO World Heritage Site status for the entire citadel site.