Thanks to Kevin Flanigan for calling this particular article to my notice:
As he notes, “we constantly underestimate the ancients.”
And I would add another, more melancholy, reflection: The people who clearly went to a great deal of trouble erecting this thing would never have imagined that it would eventually be roughly 150 feet under the sea. It’s a solid piece of rock, but such, nonetheless, is the transience of mortal human accomplishment.