The temple complex was entered from the east through the Propylaeum (, "propýlaion") or Portico, consisting of a broad staircase rising to an arcade of 12 columns flanked by 2 towers. Most of the columns have been toppled and the stairs were entirely dismantled for use in the nearby later wall, but a Latin inscription remains on several of their bases stating that Longinus, a lifeguard of the 1st Parthian Legion, and Septimius, a freedman, gilded their capitals with bronze in gratitude for the safety of Septimius Severus's son Antoninus Caracalla and empress Julia Domna.