This is the Hancock Tower in Boston’s back bay: It’s easily my favorite building in the city. It was designed by I.M.Pei’s firm of architects—but not, I believe, by I.M. Pei himself. Most long-time Boston residents remember that when it was first constructed, the large sheets of glass in the windows began to rain down on the streets below. Sheets of plywood were used to replace the missing windows, and there was a long and expensive lawsuit.