The Second Empire style is a good fit for high-class rowhouses, because it was created specifically to stuff the most usable volume into the least taxable building. Supposedly it came about because houses in France of Napoleon III’s time were taxed by the area of the rooms, but attics were not counted in the calculation. All the space above the roofline was dismissed as attic by the law; therefore, if the roof could bulge out to make an attic the same size as the other floors, you got an extra floor tax-free. Americans adopted the style because they liked the way it looked and the way it solved the practical problems of space.
This row of seven houses drops a few feet after the first three. Manchester is a flat neighborhood, but only by Pittsburgh standards. Old maps show that the row was built between 1872 and 1882.
A very clever detective might deduce that these pictures were taken on two different visits.