There were always certain spots hallowed by tradition as particularly favourable to intercourse with the dead, or even as being actual entrances to the lower world. For instance, at Heraclea in Pontus there was a famous [Greek: psychomanteion], or place where the souls of the dead could be conjured up and consulted, as Hercules was believed to have dragged Cerberus up to earth here. Other places supposed to be connected with this myth had a similar legend attached to them, as also did all places where Pluto was thought to have carried off Persephone. Thus we hear of entrances to Hades at Eleusis,[45] at Colonus,[46] at Enna in Sicily,[47] and finally at the lovely pool of Cyane, up the Anapus River, near Syracuse, one of the few streams in which the papyrus still flourishes.[48] Lakes and seas also were frequently believed to be entrances to Hades.[49] The existence of sulphurous fumes easily gave rise to a belief that certain places were in direct communication with the lower world. This was the case at Cumae where AEneas consulted the Sybil, and at Colonus; while at Hierapolis in Phrygia there was a famous "Plutonium," which could only be safely approached by the priests of Cybele.[50] It was situated under a temple of Apollo, a real entrance to Hades; and it is doubtless to this that Cicero refers when he speaks of the deadly "Plutonia" he had seen in Asia.[51] These "Plutonia" or "Charonia" are, in fact, places where mephitic vapours exist, like the Grotto del Cane and other spots in the neighbourhood of Naples and Pozzuoli. The priests must either have become used to the fumes, or have learnt some means of counteracting them; otherwise their lives can hardly have been more pleasant than that of the unfortunate dog which used to be exhibited in the Naples grotto, though the control of these very realistic entrances to the kingdom of Pluto must have been a very profitable business, well worth a little personal inconvenience. Others are mentioned by Strabo at Magnesia and Myus,[52] and there was one at Cyllene, in Arcadia. In addition to these there were numerous special temples or places where the souls of the dead, which were universally thought to possess a knowledge of the future, could be called up and consulted--e.g., the temple at Phigalia, in Arcadia, used by Pausanias, the Spartan commander;[53] or the [Greek: nekyomanteion], the oracle of the dead, by the River Acheron, in Threspotia, to which Periander, the famous tyrant of Corinth, had recourse;[54] and it was here, according to Pausanias, that Orpheus went down to the lower world in search of Eurydice.