Row houses are found in many cities, and proliferated in Baltimore providing affordable housing for the working class. The term “row house” is derived from the common wall dividing the houses. An alley between units was typical and in the era preceding the automobile, the alley served as an access to bring horses from stables behind the house to the street.
Your kit includes two units as pictured.
Separated House and alley offered separately to add more house in the row.