The palace consisted of a daidairi (大内裏, also pronounced taidairi), a large rectangular walled enclosure which contained several ceremonial and administrative buildings including the government ministries.
The original role of the palace was to manifest the centralised government model adopted by Japan from China in the 7th century—the Daijō-kan and its subsidiary Eight Ministries.
The palace was designed to provide an appropriate setting for the emperor's residence, the conduct of state affairs, and associated ceremonial functions.
One year after Empress Genmei's succession to the Chrysanthemum Throne in Keiun 4 (707 AD), a rescript was issued deciding on the move from Fujiwara-kyo near Asuka towards the northern edge of the Nara basin.
Chang'an was in turn, like many ancient east Asian cities, based on a complex system of beliefs & laws of geomancy.
This dictated the grid system of streets, as well as the necessity for spiritually protective shrines or temples to be placed at particular cardinal directions around the city.
In accordance with this system, the palace was placed at the northern end, on an extended line from Suzaku Street, the main thoroughfare running north–south straight through the centre of the city.
The primary buildings of the palace compound were the Daigoku-den, where governmental affairs were conducted, the Chōdō-in where formal ceremonies were held, the Dairi, the emperor's residence, and offices for various administrative agencies.
In the later Nara period, the audience hall was erected in the eastern part, at the south side of the imperial domicile.
[4] Heijō Palace was the main event site of Heijo Relocation 1300 Year Festival (平城遷都1300年祭, Narasento 1300-nen-sai) in 2010, and the First Great Hall (第一次大極殿, First Daigokuden) was restored for the occasion.
The main avenue was approximately 75 metres (246 ft) wide and extended north for 3.7 kilometres (2.3 mi) up to the Suzaku Gate (朱雀門, Suzakumon).
The southern open spaces was part of the main avenue, and the Nijo Oji (二条大路, Nijō-Ōji), the second great street, approximately 37 metres (121 ft) wide was extending in the east–west direction in front of the gate.
The hall was thought to have been a two-storey Chinese-style structure with a hipped and gabled roof, and an open front façade having no doors.
The upper part of the interior of the hall was painted with symbols of the Chinese zodiac such as the Tiger, the Horse and the Ox alongside the walls, and floral pattern on the ceiling.
The paintings were executed by the renowned painter Atsushi Uemura based on designs from the Nara period.
This was an important item that symbolised the imperial office, and at state events such as the enthronement and New Year's Day ceremonies the emperor proceeded to the audience hall and took his seat on the throne.
The reconstructed model of the Takamikura was made after experts consulted various literature and historical materials, and based on the throne in the Kyoto Imperial Palace which dates to the Taishō era.
This area, stretching northward from the centrally located Great Hall of State, is believed to have been the site of the Office of Foods.
This office stocked foods other than the rice that was paid as tax, and was in charge of providing meals for state banquets and rituals held in the palace.
Surrounding a large well, itself provided with a roof and from which numerous eating utensils have been excavated, stood a group of buildings used as offices and storehouses.
The first inscribed wooden tablet recovered from the palace site was found in 1961 in a rubbish pit belonging to this office.
In the vicinity of the site, Empress Shōtoku had the "Jewelled Hall of the East Palace" constructed, in which banquets were held.