The Antrum of Initiation, Baia, Italy Content from the guide to life, the universe and everything

The Antrum of Initiation, Baia, Italy

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A Roman fresco.

The Antrum of Initiation, or Great Antrum, is a complex of artificial tunnels excavated into the volcanic rock at Baia (the ancient Roman resort town of Baiae) on the northern side of the Bay of Naples in Italy. The Bay of Naples is perhaps most famous as the site of the Roman city of Pompeii. The area is also known for the town of Cuma (Roman Cumae), the home of the Sybil in Virgil's Aeneid and also one of the legendary landing places of Daedelus. Although Baiae was known principally as a pleasure resort in late Republican and Imperial times, it was also the location of a quite extensive temple centre, of which the Antrum is the most obscure, although perhaps the most important part. Since its rediscovery in the 1960s, the Antrum of Initiation has been closed to the public due to its extremely narrow, rubble-filled passages as well as the high temperatures and noxious fumes in its depths. In May of 2001, Robert Temple was permitted to explore the Antrum once again and found that the temperatures in the depths had dropped to a bearable level since the initial explorations of the 1960s.

A Description of the Antrum

The Antrum's entrance is a descending tunnel slightly more than half a metre wide and what the excavator of the Antrum, RF Paget, describes as 'walking height' although the original height was revealed by excavation to have been 2.5 metres. This tunnel begins in a complex of temples and ancillary structures cut into the face of the ridge. The entrance tunnel continues on an orientation of 270° from north for almost 125 metres. There are niches for lamps cut into the walls of this passage on alternate sides every 2.5 metres. Just before the end of this section of the tunnel there is a little jog which hides the next section of the tunnel from the visitor until the bend is passed.

At the end of the entrance tunnel there is a fork with a pivoting door which could allow various ways to be shut off. The left passage continues on the same orientation as the entrance tunnel. The right passage has an orientation of 290° and becomes stairs leading down. Paget named the branching point of the tunnel 'The Dividing of the Ways'. The right fork is 46 metres long. Beyond this point the tunnel reorients to 300° and is flooded with water.

From the edge of the water in the right hand fork, as well as the underwater route, there is another opening to a passage which rises sharply to end in a chamber excavated in the rock. From this chamber there is another descending passage which led to the opposite side of the flooded passage. The flooded passage was found, on investigation by scuba divers, to be fed by a pair of springs.

The left-hand branch at the Parting of the Ways divides into two passages which run parallel to each other but at different levels to also meet with the chamber. Paget interpreted the doubling of these tunnels as an aspect of the ventilation system of the complex. In the depths of the Antrum the high temperature and the air filled with volcanic fumes gives a definite Underworld flavour.

This complex series of tunnels could lead a person down the entrance tunnel, down the right fork at the Parting of the Ways, down the stairs to the water's edge, across the water (if the water level were lower), up the second passage to the chamber, and back out to the entrance tunnel by the left fork.

Virgil's Cumaean Sybil

In the Aeneid, the great Roman Epic by Virgil, there is a description of a journey to the Underworld that may or may not have a bearing on an understanding of the Antrum of Initiation. Aeneas, Virgil's hero, spends most of Book VI being led by the Sybil, or Prophetess, of Cumae, on a tour of the Land of the Dead. This tour with the Sybil as guide was the inspiration for the similar tour that Dante took, with Virgil as his guide, in the Inferno.

Book VI begins with Aeneas, after leaving Dido of Carthage1, making a trip to the Temple of Apollo at Cumae to consult with the Sibyl. From the Temple, Aeneas descends into the Antrum of the Sibyl (not the Antrum of Initiation), which may still be visited (without the sibyl) at Cuma. The sibyl recommends that Aeneas finish up a bit of business2 with his crew back on the beach and then take a quick trip to the Underworld. After his business, Aeneas meets again with the sibyl on the shores of Lake Avernus, an ancient volcanic crater-lake, and following appropriate sacrifices, and after the wooded hills open, they descend into the mouth of a huge cavern. No remains of such a cavern have been found on the banks of Lake Avernus; presumably the hills closed again behind Aeneas.

Immediately the journey becomes surreal. In the outside world, the Sun is rising, but in the cavern it is eternal night. Surprisingly, Aeneas is walking through groves of trees, meadows of grass, and valleys with streams flowing through them. All of the imagery is of huge open spaces and vast crowds of shades of the dead. Aeneas follows the sibyl past a number of rivers of Hell, crossing the Styx with Charon the Boatman, meeting the three-headed dog Cerberus and finally coming to a fork in the road. The right-hand road leads to Elysium and the left-hand down to Tartarus. Aeneas and the sibyl take the right hand road to Elysium where the hero meets the shade of his father. After the meeting they are faced with two exits, also mentioned in Homer's Odyssey, Book 19. One gate is made of horn and through it the dead send true dreams to the living. The other gate is made of ivory; through it false dreams are sent by the dead. Aeneas' dead father sends him home through the second gate.

Paget's Investigation and Interpretation

The Antrum was discovered and its excavation was led by RF Paget. For much of the 1960s, Paget and his team cleared and explored the tunnels and ancillary buildings of the complex trying to come to some understanding of the purpose of such an elaborate underground structure. After years of studying the Antrum, and in comparison to Book VI of the Aeneid, and also taking into account a mention by Strabo of an 'Oracle of the Dead' close to Lake Avernus, Paget came to a tentative but quite startling conclusion.

By examining the course that a visitor to the Antrum would likely follow, it became apparent to Paget that much of the route paralleled Virgil's description of Aeneas' trip to the Underworld. The initiate would descend gradually a long tunnel which finally dropped suddenly to the bank of an underground river. There, Paget speculated, a small boat would be waiting to carry the initiate across the river Styx. From the other side of the river, the initiate would ascend a winding path to a large room in which he would meet with a theatrically presented shade of a dead loved one. After the consultation, the initiate would be faced with a pair of corridors, the one on the left descending steeply and the one on the right, the exit, rising gently back to the upper world. The Styx would only be crossed one time, just as Aeneas only crossed it one time.

The Mystery of the Mystery

It is perhaps impossible to ever know the answers to a number of questions about the Antrum of Initiation: What was involved in the Mysteries that took place deep underground? Was the Antrum a place where people were initiated into those Mysteries? When did they start? When and why did they cease? Was Virgil, who lived nearby, an initiate of the mysteries? Was there (in parallel with Aeneas' trip to the Underworld) an Oracle of the Dead deep underground? A manuscript preserved in Count Nikolai Tolstoy's private collection and published by Robert Temple in 1984 provides a description of a careful exploration of the Baia area in the 1600s but the Antrum of Initiation went unnoticed. Sometime in the Roman Imperial period the Antrum was, with great effort, intentionally sealed. It is unknown exactly when, why, or by whom. But there was some sort of association of Baia with a sibyl into the 19th Century, as evidenced by JMW Turner's painting The Bay of Baia with Apollo and the Sibyl.

In 2002, Robert Temple tried to bring the Antrum of Initiation into the new age with his book, Netherworld. Sadly, on his web page about Netherworld, Temple gives no mention or acknowledgement of RF Paget and his years of work clearing rubble from the long tunnels and providing the basic interpretation which Netherworld repeats. While impossible to foresee accurately, it is doubtful that Temple's speculative conclusions will endure as long as has the Antrum of Initiation and its Mystery.


  • RF Paget, 'The Great Antrum at Baiae: A Preliminary Report', Papers of the British School at Rome, XXXV (1967), 102-112.

  • RF Paget, In the Footsteps of Orpheus: the Story of the Finding and Identification of the Lost Entrance to Hades, the Oracle of the Dead, the River Styx and the Infernal Regions of the Greeks, Robert Hale, London (1967).

  • CG Hardie, 'The Great Antrum at Baiae', Papers of the British School at Rome, XXXVII, (1969), 14-33.

  • CG Hardie, Appendix to P Vergili Maronis Aeneidos, Liber Sextus, Clarendon Press, Oxford (1977), pp. 279-286.

  • RG Austin, Commentary to P Vergili Maronis Aeneidos, Liber Sextus, Clarendon Press, Oxford (1977), p. 56.

  • Robert Temple, Conversations with Eternity, Rider, London (1984), pp. 175-178.

  • Robert Temple, Netherworld: Discovering the Oracle of the Dead and Ancient Techniques of Foretelling the Future, Century, London (2002).

1See a more modern treatment of Aeneas' mistreatment of Dido in 'Dido and Aeneas' by Henry Purcell.2Aeneas' business was to bury one of his crewmen who had died during the visit to the Sybil. Aeneas later met the crewman's shade in the Underworld.

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