Their original purpose is shrouded in mystery, but Historic England, which describes the caves as a “grotto”, believes they were probably built in the late 18th or early 19th Century - hundreds of years after the Templar order was dissolved.
So not Templars then, or 700 years old, and clearly not a rabbit’s hole either.
It is in England though, so at least part of the headline is correct.
By the craggy hill-side,
Through the mosses bare,
They have planted thorn-trees
For pleasure here and there.
If any man so daring
As dig them up in spite,
He shall find their sharpest thorns
In his bed at night.
Stonehenge isn’t all that unusual apart from being build out of stone. We know of many other similar structures. Preservation is the key issue for their lack of popularity and visibility as the majority were/are earthworks (wood/earth constructions).
The real question is how soon the History Channel show The Curse of Oak Island will try to connect the cave to Oak Island. That show name-drops “the Knights Templar” as often as politicians used to refer to “9/11”.
Though that is a bit like saying “a gold Apple Watch isn’t unusual apart from being made out of gold”. The relative energy requirements to build stone monuments in the Beaker* era were very high, which is presumably why they were much less common. We can at least conclude that Stonehenge and Ggantija (which is ca. 1000 years older) were very important to the people that either built them or had them built.
*Unlike @wrecksdart I am taking this quite seriously. The Templars, excuse me while I indulge in sarcastic laughter.
I can’t help thinking a lot of it is because Stonehenge is just off the A303, one of the main roads to the South-West, while Avebury has far less traffic pass by it.
“religious importance to contemporary pagans” though, cf Wikipedia -