Harvard Square is no stranger to change, but the historic neighborhood seems to be undergoing a particularly fast overturn, with more than 10 percent of retail spaces currently vacant. The empty buildings add to the list of local places that are now memories of the past: the Harvard Square Theater, Tealuxe and Crema Café.

In for Jim Braude, Adam Reilly was joined by Denise Jillson, executive director of the Harvard Square Business Association, Cathy Botindari, co-owner of Colonial Drug, which moved to Newton in 2013 after 60 years in the Square, and Shoshanah Garber, the owner of Black Sheep Bagels, which opened in the Square last summer.