Like a Tourist?

From time to rare time I see the town as through Tourist eyes, or an infrequent visitor; which I suppose, for the last few years, I have been.

I'd collected a job or three so went downtown to do them. On a whim I went on, rather than back after the last call.  LOTS of change. I hadn't  taken a Book and I can not abide sitting over a cuppa doing dammall, so I read, thus no cuppa today.  Well not one somebody else made.

En route (Coincidentally "En Route" was the title of our first French Text Book @ School) back to the Car I noticed this on one of Barclay's Bank building Blocks. Alliteration yet?

I suspect it's a Mason's Mark.  NOT the Free variety, the paid for Trade variety.  I further suspect they haven't a clue what it is or how long it's been there.