Heijō Palace in Nara, was the Imperial Palace of Japan (710-784 AD), during most of the Nara period. The Palace was located in the north end of the capital city, Heijō-kyō. The 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."
After Empress Genmei's succession to Imperial Throne in 707, there was much discussion about the transfer of the palace. A year later, a rescript was issued deciding on the move to Nara. In 710, the new capital officially takes over, but the completion of the palace had to wait further. (Written Heijō but also pronounced Nara at the time, the land gains its synonym, Nanto as opposed to Kyoto, the capital in the North, centuries later.)
The city, and the palace grounds, was based largely on Chang'an (present-day Xi'an), the capital of China during the Tang Dynasty, which was contemporary to the time when Nara was capital of Japan. 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.
It takes 15 or 20 minutes to walk from Yamato-Saidaiji Station to Heijō Palace. And between May and August in 2010, the free shuttle bus runs between Yamato-Saidaiji Station, JR Nara Station and Heijō Palace every 10 or 15 minutes.