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. Finally 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 conducted mainly since the late 1970s.