The library has a Flickr stream with wonderful old photos of Roxbury during the period 1860-1935.
Some of the better known are of still (barely) extant buildings, the Kittredge House
and soon to be HBI headquarters, Torrent Six on Eustis Street.
Here's furniture store Ferdinand's in an early iteration:
Lithographer Louis Prang's House on Centre Street with Mr. Prang himself in the front yard
The Old Guild Home on what was the corner of Bartlett and Washington
There are dozens of others. Dot and JP have their Boston Pictorial Archive Flickr streams too.