In addition, old roof tiles used in the Asuka period through the first half of the Nara period were excavated from the Kaioryu-ji Temple precincts, which indicated that some preceding buildings might exist before the capital relocation to Heijo-kyo.
なお、海龍王寺境内からは飛鳥時代から奈良時代前期の古瓦が出土しており、平城京遷都以前に何らかの前身建物が存在した可能性が指摘されている。