The page above, from “Apartment Houses of the Metropolis” says that the twin buildings shown – 616 and 628 West 137th Street – were the first concrete-frame apartment houses in New York. If so, they soon had company, as this book was published in 1908 and I know of at least one other concrete apartment house completed that year.
That book was exactly what it sounds like: a compendium of modern apartment buildings in New York, showing off what could be done under the New Tenement Law to create livable multiple dwellings. In other words, it was an attempt to influence developers and the public away from the known failures of Old Law Tenements.
The vast majority of apartment houses constructed at that time, which today make up the older portion of the now-coveted “pre-war” apartments, had roughly similar ornamented masonry facades. They mixed in a bunch of styles, generally being true to none of them, and created a lot of pigeon landings that are fodder for repair projects in the twenty-first century. If you look at the floor plan, the bedrooms (“chambers”) are small, but the apartments are otherwise pretty nice middle-class dwellings.
Part of the uniformity of the facades of these apartment houses can be seen in the fact that if you didn’t know these two buildings were concrete-framed, you’d never guess. They look just like their steel-frame and bearing-wall contemporaries. Here’s a recent view of the block:
The building on the left is 616 West 137th, one of the concrete twins. Compare it to the building directly across the street, which has no particular claim to fame. Both have ornate masonry facades, both have a fire-escape set in a niche on the front facade with a big decorative arch across the top. There are differences, of course, but none that hint at different structure. 616 West has lost its cornice, and its neighbor has not, but those are artifacts of aging and maintenance, not original construction.