The building was a center of the cult of the Emperor Augustus and the headquarters of the Collegium Augustalium. The interior is composed of one large room divided into three naves by four Tuscan columns which support the roof, with light entering via a skylight. At some stage a room was made by constructing two walls connecting the back wall to the two rear pillars. The room, which served as a sacellum, was raised above the rest of the hall and was completely decorated in the fourth style.