Heian Palace

The Heian Palace (平安宮, Heian-kyū) was the original imperial palace of Heian-kyō (present-day Kyoto), then the capital of Japan. Both the palace and the city were constructed in the late 700s and were patterned on Chinese models and designs. The palace served as the imperial residence and the administrative centre for most of the Heian period (794–1185).

Located in the north-central section of the city, the palace consisted of a large, walled, rectangular Greater Palace (the Daidairi), 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 (Dairi). In addition to the emperor's living quarters, the Inner Palace contained the residences of the imperial consorts and 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 – known as the ritsuryō system, where the bureaucracy under the emperor was headed by the great council of state (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. While the residential function of the palace continued until the 12th century, the facilities built for grand state ceremonies began to fall into disuse by the 9th century. This was due to both the abandonment of several statutory ceremonies and procedures and the transfer of several remaining ceremonies into the smaller-scale setting of the Inner Palace.

From the mid-Heian period, the palace suffered several fires and other disasters. During reconstructions, emperors and some of the office functions resided outside the palace. This, along with the general loss of political power of the court, acted to further diminish the importance of the palace as the administrative centre. In 1227 the palace burned down and was never rebuilt. The site was built over so that almost no trace of it remains. Knowledge of the palace is thus based on contemporary literary sources, surviving diagrams and paintings, and limited excavations.

The palace was located at the northern centre of the rectangular city Heian-kyō, following the Chinese model of the Tang dynasty capital of Chang'an. The model had been adopted already for the Heijō Palace in the earlier capital Heijō-kyō (in present-day Nara) and the short-lived interim capital of Nagaoka-kyō.

The main entrance to the palace was the gate Suzakumon (35°0′49″N 135°44′32″E / 35.01361°N 135.74222°E / 35.01361; 135.74222), which formed the northern terminus of the great Suzaku Avenue, which ran through the centre of the city from the gate Rashōmon. The palace thus faced south and presided over the symmetrical urban plan of Heian-kyō. In addition to the Suzakumon, the palace had 13 other gates located symmetrically along the side walls. A major avenue led to each of the gates, except for the three along the northern side of the palace, which was coterminous with the northern boundary of the city.

The south-eastern corner of the Greater Palace was located in the middle of the present-day Nijō Castle.

Less than ten years after a presumably politically motivated move of the capital from Heijō-kyō (平城京) (on the site of present-day Nara) to Nagaoka-kyō (長岡京) (approx. 10 kilometers to the south-west of Kyoto), Emperor Kanmu decided to move the capital again, likely due to frequent flooding of the Nagaoka-kyō site. In 794 the court moved into this new capital of Heian-kyō, where it was to stay for more than 1000 years. The palace was the first and most important structure to be erected at the new capital, but it was not completely ready by the time of the move; the Great Audience Hall (大極殿, Daigokuden) was completed in 795, and the government office in charge of its construction was disbanded in 805, though work on the place was still incomplete. Construction of the palace and imperial family residences was a major expenditure for Kanmu's administration, accounting for the majority of revenues gathered during his reign, according to a 10th-century source. The powerful immigrant Hata family may have influenced and financially supported the decision to move the capital to Heian-kyō, closer to its power base. Later sources claim that the new imperial residence occupied the site of a former Hata leader's residence.