Many buildings in Boston (and neighboring Cambridge) are old, and require regular maintenance to the exterior brick, granite steps, stone foundations, etc. So I was not surprised to see these piles of sorted construction materials in the yard of Radcliffe College (Harvard U).

All around me was the steady clink clink of bricklayers and masons restoring the steps and walls of one of the ancient colleges.

But upon closer inspection, I noticed this sign: