Do you ever start to notice odd patterns, certain repeating motifs, in your surroundings?
Consider the early apartment buildings pictured below. These are "4-family flats", each built to house one family per floor. There are 4-family apartment houses all over Park Slope, often with full-height, 3-sided bays. These apartments were frequently built in series, several buildings in a row, with continuous facade banding and cornices.
But beyond the general similarities amongst 4-family apartment buildings, one finds virtually identical buildings in different parts of Park Slope. The apartment buildings shown here all have light-colored brick over a brownstone first floor, with brownstone detailing above; arched windows at the 4th floor only; terra-cotta panels featuring "Green Men" (foliate heads) or medallions; and clusters of narrow columns framing the doorway.