Pluto was the Roman underworld god, most certainly derived from the Greek god Hades. He abducted Prosepina for his queen. The three-headed dog Cerberus was set to guard the gates of Hades and through the kingdom flowed the two rivers of death, the Cocytus and the Acheron, which could only be crossed by the ferryman Charon. According to Roman tradition the entrance to the underworld was at Avernus in Rome where the Christian church of St. Maria del Inferno was constructed. A.G.H.
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 206