"Shugaisho" (an ancient encyclopedia in 14th century) says it was 'niju-kaku-kyu-ken' (a two storied house with nine bays), and experts say it was a two storied gatehouse with nine bays and five openings.
『拾芥抄』に「二重閣九間」とあり、9間5戸の重層門であったとされる。