Heijō Palace (平城宮, Heijō-kyō) was the imperial residence in the Japanese capital city Heijō-kyō (today's Nara), during most of the Nara period. The palace, which served as the imperial residence and the administrative centre of for most of the Nara period from 710 to 794 AD, was located at the north-central location of the city in accordance with the Chinese models used for the design of the capital.
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. Inside this enclosure was the separately walled residential compound of the emperor or the Inner Palace. In addition to the emperor's living quarters, the Inner Palace contained the residences of the imperial consorts, as well as certain official and ceremonial buildings more closely linked to the person of the emperor.
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 great affairs of state, and the accompanying ceremonies.
After the capital was moved to Heian, the palace structures were either moved there or suffered several fires and other disasters and disappeared. The site was built over for agriculture that almost no trace of it remained, however, the location was still known. Excavations started in the 1970s and large-scale reconstruction based on contemporary literary sources and excavations starting in the 2000s.
The excavated remains of the palace, and the surrounding area, was established as a UNESCO World Heritage Site in 1998 along with a number of other buildings and area, as the "Historic Monuments of Ancient Nara."