Colonial Americans, if they could afford it, liked to emulate the fashions of London and the style and manners of English country society while at the same time thinking of themselves as distinctly American. The houses they built reflected this ongoing cultural tension. By the mid-eighteenth century, Americans had developed their own version of the bourgeois English countryseat, a class of estate equally distinct in social function and form from townhouses, rural plantations, and farms. The metropolis of Philadelphia was surrounded by a particularly extraordinary collection of country...