In its earliest phase the nymphaeum consisted of a rectangular room with a tri-apsidal fountain set in its northern wall flowing into a rectangular basin along the length of the same wall. After an earthquake in CE 77, the nymphaeum was rebuilt between 98 and 117. The nymphaeum was internally dived by a courtyard with a room to the south containing an apsidal fountain and rectangular basins. In this phase, the nymphaeum measured 45 m long and 15 m wide. After its destruction in the earthquakes of the late fourth century, the nymphaeum was rebuilt as a three-aisled basilica with apses along the southern wall. This structure was used as a temporary church between 370 and 410 during the construction of the ecclesiastical precinct to the west. It was abandoned in the mid seventh century.