The excavation revealed that many ditches, which were stretching to the east, west, north, and south directions (Seihoi), existed in a wide area around the Koki Naniwa no Miya Palace in the Nara period and many structural sites were also placed at Seihoi.
発掘調査によれば、奈良時代の後期難波宮周辺には正東西南北方位（正方位）にのびる溝が広い範囲で多数検出されており、建物跡も正方位に築かれたものが多い。