Entering the Antrum

The trench forming the start of the Great Antrum was once covered over and situated under the floor of the Greek Temple. Thick streaks of waxy-looking stalagmites line the sides of the trench. This is due to centuries of exposure and water finding its way down here. The Serino aqueduct which runs over the Great Antrum was ruined in the 472 AD Pollena volcanic eruption. Centuries of water cascaded down.

Once we have dropped below the surface buildings, which sit on a terrace 23 metres (75 ½ feet) above sea level, we are in the narrow trench, itself just one metre wide (3 feet 3⅜ inches).

Where the tunnel enters the hillside it narrows even more, to about 0.55 of a metre (21 inches) – shoulder width, as the picture of Michael Baigent shows.

The tunnel continues into the volcanic crater wall in a perfectly straight line for 124.5 metres (408 ½ feet), maintaining its narrow width and a height of about 1.8 metres. Centuries of crystalline deposits line the floor to reduce the height from its original one.

What is an Antrum anyway?

Antrum is simply Latin for a cave. The term ‘Antrum of the Sybil’ for the tunnel at Cuma had been named previously, probably by its discoverer Amedeo Maiuri in 1932. 

By association, Doc Paget called this tunnel ‘The Great Antrum’. It certainly exceeds the length of that seen at Cuma and is far more impressive.

The Roman Pipe

As Doc Paget observed in his book “In the Footsteps of Orpheus”, a Roman pipe once sat on a horizontal ledge, which we can see the supports for on the left of the trench. Inside the tunnel we can see a ledge has been crudely hacked for the pipe to continue on.

Doc had an idea that this was the steam inlet, as the pipe and ledge simply stop, somewhere near where the back of the Tholos tunnel is situated. He imagined the pipe then crossed the antrum and went into the Tholos.

Those that have considered this theory find it unlikely and the Tholos pipe shows no sign that a pipe ever joined onto it, in fact the reverse, cement obscures the end of the Tholos pipe.

In 2014 Peter Knight and Graziano Ferrari removed the trash that was presumably left by the 2003 film crew.

The stalagmites have given the trench a wax-like appearance
Stalagmites give the trench an eerie wax-like appearance

Temple & Baigent

Robert Temple & Michael Baigent descended together in 2001. Official permission had been granted after 20 years of delicate negotiation. Robert Temple later made a film aired by National Geographic in 2003.

Today access is hazardous, requiring a tall ladder.

Forbidden History


Majoring on cheap sensationalism, Director Bruce Burgess and front man Andrew Gough filmed at Baia in 2014 as part of the ‘Forbidden History’ series. 

They concluded that the purely Roman military site at Lake Avernus, often described historically as the site of the Oracle of the Cumaean Sybil, better suited their notion of what the Oracle of the Dead should be.

Italy’s Invisible Cities (BBC)


Historian Michael Scott and front man Alexander Armstrong briefly explored the tunnels in an episode of Italy’s Invisible Cities.

Here Peter Knight escorts Alexander Armstrong into the tunnel complex.

Alexander Armstrong saw a scorpion at the underground water course and fled for the entrance. The cameraman continued a little further but likewise took fright at the sight of a small hole that required him to crawl through.

None of this prevented them from saying before they entered, for the very first time, that it was nothing but a steam channel for the Roman Baths, the conventional line.

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