This is one of the best preserved monuments in Hierapolis. It dates back to the time of Emperor Septimius Severus, in 193. Most notable are the entrance arches and interior corridors covered by barrel vaults. There are 26 rows of marble steps up the cavea, on the third floor. In the centre there is a semicircular seat, reserved for famous people. It also highlights a frieze with mythological scenes of Apollo and Artemis.