One of the purported Round Tables - Kings Knot, at Stirling (once within the Kingdom of Manann/Manau)

Tabled Round

   Several different historians have proposed that the Round Table of the legends was actually a reversal of the adjective and not a round table but a tabled round. In other words, one of the many rotunda henge monuments scattered around the Isles. The most prominent contender is Stonehenge principally due to its size and prominence and its role in the religious mysteries of the past. One of the authors of this theory is John Darrah in his book "The Real Camelot". Note the round tabled plan of Stonehenge.
   Other writers include Goodrich in her book "King Arthur" and recently, Carroll in his book "Arturius- A Quest for Camelot".
   Standing at the foot of the rock on which Stirling Castle stands is an impressive earthwork structure known today as The Kings Knot, but to which the name Round Table became attached as far back as 1370 CE according to Carroll. It was certainly added to and altered by the Stuart Monarchs in later centuries, but nevertheless existed before their time.
Another possible candidate for this is the round amphitheatre at Caerleon which is associated with Arthur in Geoffrey's Historia and many later texts and may represent Leodegrance's gift of the Round Table on the marriage to Guinevere.

Stonehenge Plan