These are the ruins of the palace of Empress Kogyoku, where the Isshi Incident occurred. In 643, the empress moved from the temporary palace of Oharidano-miya to this new palace. Palaces at the time were typically roofed with thatching or cypress bark. But this palace used high-grade wooden planks instead, hence its name Itabuki (“wooden roofing”). This is also where the palace was built when the empress ascended the throne for the second time, as Empress Saimei. Later, Empress Jito also built a palace in the same spot. This must have been a strategically important location, as the remains of several palaces have been found here layered one atop the other.