And the funny thing is, when I was researching about Merlin on Wikipedia, I came across one mythological story that claimed Merlin actually BUILT the structure in question.
TRANSCRIPTION COURTESY OF JOSEPH HOUK - [495; The Britons have turned the tide!] (Random Soldier, raising his sword in triumph) "They're on the run!" (Arthur, looking on at the figures in the background) "I say, Merlin, it appears that some are pillaging thy home!" (Merlin, suddenly realizing) "MY WORD! If they destroy the waters that I possess… [KABOOOOM] Oh dear…" (Arthur, consoling him) "Fear not, my friend. I shalt arrange to have thee take up residence at my castle!" (TT, from behind the rocks with Matt & Bethany) "Evidently those 'strange waters' included chemicals that were highly explosive when mixed together!" (MG) "Everyone okay?" (BG) "I… think so!" (MG) "How bad is the damage…?" [The three peek out from behind the rock… and are stunned] (BG) "Oh… shit… He lived THERE???" [Aerial view of the wreckage reveals… Stonehenge!] (TT) "Um… right… Let's just keep this between ourselves, eh?"