[Jawnadelphia]

The I-95 cooridor, Mid-Atlantic cities:
Philly-Baltimore-and their little cousin Wilmington, DE all have large parts of their cities -- outside of downtown areas (Philly's Center City is obviously huge), that look pretty identical. Red brick rowhouses, big old-Victorian era mansions--twins, brick sidewalks, etc.
If I recall correctly, Philly and Baltimore's housing stock are very similar and unique compared to other big cities as far as rowhouses making up the predominate % of the housing stock.
Makes sense--old East Coast cities, a lot of history, similar industrialization, working class neighborhoods, etc etc. And geographically, Philly and Baltimore are only 105 miles a part (and Wilmington, DE is ~30 miles to Philly, but only 74 miles to Baltimore).