There are five gates to Ngo Mon with the central gate being reserved for the kings only. It is 4.2 meters high and 3.7 meters wide. The two adjacent gates on both sides of the central gate are exclusively for court officials. The other two outer gates are used for servants and member so the royal entourage. On top of the arch is Five phoenix Tower which was formerly the place where the king was also the place where ceremonies were organised to announce the names of laureate candidates from royal examinations before those names were put on the notice board hanged on the Phu Van Lau (Phu Vawn tower).

In the reign of the Nguyen kings the Ngo Mon Gate was opened only when the kings were passing by or the kings received foreign ambassadors.