As an undergrad while taking an Art History Survey course the professor had a habit of showing slides, say a Carolingian stone monument or a piece of jewelry etc and then ask us simple questions, what is it? In the middle of one long lecture on early Celtic art or some such which included lots of Barrows etc, she showed a picture of a stone wall covered in ivy. Asking what is it? Lots of speculating, theorizing etc, to which she replied with a straight face," This is the location of the last confirmed sighting of the king of the faeries." then click on the next slide without missing a beat. BTW she was extremely humorous-less throughout the year, very strict etc this was her one treat. A simple plain old farmer's wall to which we'd applied so so much speculation.