20 facts about pianos and Boston

On the occasion of the massive public piano installation, a look at some key numbers.

Photo credit: Symphony Hall by Michael J. Lutch; MFA by Tom Herde/Globe File; play me by Luke Jerram, Symon Reynolds and K. Deviercy; piano by istockphoto; student by Chaloner Woods/Getty images; Mason & Hamlin by Jim Wilson/Globe Staff/File

Marian Daniells/Globe Correspondent