The fountain in the Christian Science Center in Back Bay, Boston.
The woman above and her husband were walking around the fountain; I was sitting inside taking pictures. She kept stopping to poke her cane or foot through, so I was somewhat alerted, and got that one. Aiming to not be creepy, I waved; and she came over and we chatted in something I couldn't quite identify. (Russian?) She pointed to various things and said words, and I repeated them; there were lights at the base of the water jets, and some of the words were identifiable as related to "cyan" and "rose", so I guessed we were talking about colors. Eventually her husband dragged her away (somewhat literally). It was great fun!