I don't think I've seen this one before. Not sure where this was (and the Halifax Archives people aren't either). Maybe that's on Hollis next to the old BMO building that was replaced by the current office tower?
Source
This building looks potentially quite old, maybe one of the older commercial buildings of this style in the city with that level of detail. Maybe as late as 1870, but maybe from as early as 1820-1840?