After defeating Mac Dynasty, Trinh Tung proclaimed himself as Binh An Vuong (King Peace) and stipulated that King Le could tax only 1,000 communes. King Le had only 5,000 troops, 7 elephants and 20 dragon boats. At that time, King Le was a nominal king, while the real authority was taken by the lord Trinh.
With limited perks and power, King Le was unable to preserve the magnificent palaces as before. The building of new palaces is even more limited. Many palaces of King Le were abandoned. Even Nung Son Palace was not used as the place to give audience, but turned into Kinh Thien Palace to worship the heaven and earth. A couple of times in a month, the King gave audience in Can Chanh Palace, Dai Lau Institute. The two sides of the palace were abandoned for a long time which “collapsed one after another; the grass grew highly to the knee; horse manure strewed”.
Not only the palaces were abandoned, the citadel wall also collapsed. According to historical documents, at the end of the XVIII century, when the Tay Son Bac helped King Le to break the tyranny of Lord Trinh, the Imperial Citadel remained only two gates, i.e. Dai Hung and Dong Hoa. The Tay Son then helped King Le to build the Imperial Citadel from Dong Hoa Gate to Dai Hung Gate.
In contrast to the abandoned royal palaces, lord palaces were immense and splendid with gilded buildings and glistening lights and flowers. The architectural composition of lord palaces was built on a large area, mainly in the south west of Hoan Kiem Lake, stretching to the southeast of Hoan Kiem Lake, to the bank of the Nhi River, known as Red River today.
Lord Trinh’s palaces was built as the Imperial Citadel of the powerful kings. The entire area was a square surrounded by a wall with gates, i.e. Chinh Mon Gate in the south and Tuyen Vu Gate in the east viewing at Hoan Kiem Lake. Around Hoan Kiem Lake, lord Trinh built many constructions; on Go Rua (Turtle Knoll in the centre of Hoan Kiem Lake; Turtle Tower is still there nowadays), lord Trinh built Ta Vong Temple. Perhaps the most significant constructions was Ngu Long Building (Five Dragon Building) as high as 120 meters. Ta Vong Temple portrayed five dragons; the dragons were engraved with porcelain and marble.
The main area in lord palaces was a magnificent castle complex with 52 great constructions. All the palaces had two floors with many palatial doors and gilded ironwood frames. These splendid palaces were described in many domestic and foreign documents, including the famous works by Le Huu Trac “Thuong Kinh ky su” (The chronicle of the journey to the royal city). The magnificent castle complex with a multitude of fragrant flowers, leaves, rare birds, lakes, and streams and harmonic rockery, forming such a beautiful view that Le Huu Trac had to say “It looks like nothing but the paradise.”
However, the next lords of Nguyen Dynasties became tyrant, autocratic and depraved. Therefore, the Tay Son led the troops to help King Le defeat the Trinh and reclaim the authority. With the help of the Tay Son, King Le Chieu Thong escaped from the control of the Trinh. To prevent the disastrous consequences, King Le Chieu Thong then ordered to burn the entire lord palaces. The lord palaces were immense so the fire was so fierce that it spread to the residents’s houses.The fire destroyed two third of Thang Long Imperial Citadel.This is considered as the biggest fire in the history of Thang Long Imperial Citadel. The splendor architectural composition of Trinh lords, after 10 days in flames, melted into ashes.