In Travels in North America (1750), Pehr Kalm described what he saw in this area of Philadelphia: “The houses here are commonly built in the English manner. Upon investigating I found that the lowest room was entirely under ground, and its walls made of stone, although the house above it was built of brick.

It was used for a cellar, pantry, wood shed, or sometimes a kitchen and merchants occasionally kept their goods in it. There was no real, useless garret as with us in Sweden, for the building was so constructed that rooms for dwelling purposes extended up top the roof, generally with a fireplace in them, and sometimes with dormer windows.” By 1702, proximity to the port and to the markets had given enough economic value to warrant opening Elfreth's Alley. Its narrow cartway, framed on both sides by pre-Revolutionary two-and-one-half-story houses and early-nineteenth-century three-and-one-half-story houses, vividly portrays the lifestyle of most Philadelphians. Continuously inhabited since the early eighteenth century, the alley structures speak of the opportunities open to the enlarged middle classes in a thriving city. Here lived such distinguished artisans as silversmith Philip Syng and cabinetmaker David Trotter.

The earlier houses show the dark headers and rough and irregular surfaces of handmade brick and are typically lower in height, with pent eaves across the lower facade, while the later houses show the simplified detail of the Adam brothers and are also differentiated by their uniformly red and crisp machinemade brick of the early nineteenth century. Side alley doorways provide access to the rear wings—typically not kitchens but smaller rental units that further increased the density of the block. At the block's east end, Bladen's Court packs half-a-dozen houses into a rear courtyard, giving evidence of the value of land in close proximity to the port and market. The mid-eighteenth-century “Mantua Maker's House,” at number 126, is open to the public and contains materials related to the clothing trades of its period. It was one of several houses built before 1762 to provide rental income for Jeremiah Elfreth. During the nineteenth century the alley buildings housed sailors who rented garret rooms; later, they were home to numerous policemen and firemen, the workforce of the growing city. Presently its buildings are largely owner occupied.