Wandering through the garden squares and bow-fronted brick rowhouses of Boston’s Back Bay and South End neighborhoods, one soon comes across alleyways between the backs of two rows. They usually have names like “Public Alley 171” and aren’t much to look at — fire escapes, garbage cans and parking, mostly.

Essentially, these streets have become privatized because the majority of the public has abandoned them. They have nothing to attract users during the day and even less at night, but it seems that there is still some potential there.

Public Alleys 438 to 444 run between Boylston Street and Newbury Street in the Back Bay from the Public Garden to Hynes Convention Center Station, except for a block bounded by Clarendon, Newbury, Boylston and Berkeley Streets, and there’s quite a bit of space in the rear of the townhouses. It’s also one of Boston’s most important commercial neighborhoods, for both retail and office use — too say nothing of the housing costs in the Back Bay.

Because of this space in proximity to resources like the Green Line and the other amenities of the Back Bay, plus the large amount of existing foot traffic, I think there’s a good opportunity to develop the rear yards and turn the alleys into narrow streets. It would help expand much needed retail and restaurant space in a popular neighborhood and could even help add housing to a neighborhood where development is difficult because of prices and preservation.

Public Alley 443 is about 12 ft wide and would make an excellent Very Narrow Street.

What’s more is that there are a number of places in Boston where I believe this has already happened, before minimum lot sizes, minimum parking requirements and other impositions made it illegal.

Lawrence Street, in the South End, for example, is much narrower than the other cross streets in the neighborhood, with smaller, more square houses than the typical bowfronted row house with hypertrophic stair in the front.

Appleton Street is the next street over from Lawrence, going southeast.

Something similar appears to have happened in South Boston, where Story Street has been built in the block between Fifth and Sixth Streets while the block between Fifth and Fourth preserves the original block dimensions.

A similar process occurred throughout Beacon Hill, mostly on the northern, poorer side, but definitely on the southern, wealthier side. Acorn Street, which is widely cited as the “most-photographed street in Boston” is clearly this sort of street built for making rear yards developable and looks to me like it might have even been a mews at one time.

While rare in the United States, the process of putting a street through a block in order to build in the rear yard was common in Mexico City and was a feature of traditional cities in Europe and doubtless elsewhere. There are some efforts to revert to the traditional forms, however. Many cities have seen the creation of ambiguously legal accessory dwelling units or in-law apartments, while Vancouver has legalized the laneway house.