The government office of Nagaoka-kuu had three major sections. Choudou-in, Dairi and Shokanchou.
Choudou-in is the center of 'Miya' and the location of National ceremonies.
In some ways like the present House of Parliament.
Choudou-in is very long from north to south and it is covered with rectangular and square shapes.
The rectangular area in the north is called Daigokuden-in.
The square area in the south is called Choudou-in.
Choudou-in Nagaoka-kyo has 4 halls in the east and 4 halls in the west- 8 halls in total.
The remains of Nishi Daiyon Dou was found by the investigatory excavation in 1982.
It was designated as a National Historical remains in 1992 and is now maintained as a public park.