Hanoi is legendary for its tube houses that trade width for height and depth. Buildings perform what would seem to be architectural miracles by heading several stories into the air supported by such a narrow base. While space is somewhat at a premium here in the Old Quarter, some of these buildings are just freakishly narrow.
But they make up for it in depth; buildings in Hanoi extend far back from the front house you see from the street. Traditionally, the front room of the house facing the street was used for selling goods to the public.
Doing business out of the front of the house is common here. Many of the streets here in the Old Quarter are named for goods or services you can buy. Historical street names include things like “blacksmithing” and various food names. The logic was that sellers of the same feather would flock together, one right next to the other.