The designers of Heijo-kyo did not just copy Chang'an's street grid -- they imported its cosmology. The Chinese system of geomancy dictated that the imperial palace must sit at the northern end of the city, aligned with a central north-south axis. Protective shrines and temples were positioned at specific cardinal directions around the perimeter. Heijo Palace occupied the north-central position within this grid, a walled compound containing the Daigoku-den where state affairs were conducted, the Chodo-in where formal ceremonies unfolded, and the Dairi -- the emperor's personal residence. Within the Dairi, a second set of walls enclosed the Inner Palace, holding the residences of imperial consorts alongside ceremonial buildings tied directly to the sovereign. The entire arrangement was designed to manifest in physical form the Daijo-kan system of centralized government -- the Grand Council of State and its subsidiary Eight Ministries, a bureaucratic apparatus borrowed from China and adapted for Japanese rule.

Heijo Palace's seventy-five-year reign as the seat of power was not uninterrupted. Emperor Shomu, ruling during a turbulent mid-century marked by epidemic and political instability, relocated the capital twice between 740 and 745 -- first to Kuni-kyo, then to Shigaraki-kyo -- before returning to Nara. Each move triggered drastic transformations of the imperial compound. In the later Nara period, a new audience hall was erected in the eastern section of the palace grounds, south of the imperial residence. Buildings within the Dairi and government offices were replaced and renovated multiple times, suggesting not routine maintenance but fundamental reorganizations of how the court presented itself and conducted its business. The palace was a living organism, constantly rebuilt to reflect the shifting priorities of whoever sat on the Chrysanthemum Throne.

When the capital moved to Heian-kyo in 784, no one burned Heijo Palace or tore it down for materials. It was simply left behind. Some structures were relocated to the new capital; the rest were left to rain, wind, and fire. By the beginning of the Kamakura period in the late twelfth century, every building had vanished. The site became farmland. Rice paddies covered the halls where emperors once received foreign ambassadors. Yet the location was never truly forgotten -- local knowledge preserved the general boundaries of the old palace compound even as every physical trace disappeared. When systematic archaeological excavations began in 1959, led by the Nara National Research Institute for Cultural Properties, the underground remains proved remarkably well preserved. Foundations, post holes, drainage channels, and artifacts emerged from beneath the soil, mapping the outlines of buildings that had stood for less than a century but whose underground footprints endured for more than a thousand years.

Excavations since 1974 have revealed the full scope of Suzaku-oji, the great central street, confirming its width of approximately 74 meters between drainage gutters and roughly 85 meters between embankments. Beneath the Nara-period road surface, archaeologists discovered the remains of an older 23-meter-wide road, evidence of an earlier settlement. In 2010, a 70-meter-wide, 210-meter-long section of Suzaku-oji was restored south of Suzakumon Gate. The Suzakumon Gate itself was reconstructed in the late twentieth century, and in 2022 the Daigoku Gate -- the southern gate of the First Daigokuden Compound -- was reconstructed based on excavation data. The Daigoku-den Great Hall of State itself had been rebuilt for the 1,300th anniversary celebrations in 2010. Today the Nara Palace Site Museum displays the ongoing results of more than six decades of archaeological work. The entire site, along with other monuments in Nara, was designated a UNESCO World Heritage Site in 1998. The palace that vanished into rice paddies has been coaxed back out of the earth, not as a ruin but as a reconstruction -- a physical argument that seventy-five years of imperial grandeur were worth remembering.