This is 1905 or so, looking west on 42nd Street from Grand Central. There is a lot going here.
The huge masonry pile foreground right is Grand Central Station, the 1898 renovation and expansion of the original 1872 Grand Central Depot. Architecturally, we’ve got three or four styles here, none of them particularly happy about being next to the others. The canopy in front looks like a sheet-metal after-thought, to keep first-class passengers dry while they wait for a horse-drawn cab. The big building across 42nd Street on the left, with the skeletal cornice, is the Lincoln storage warehouse, a big fireproof building for business record storage. It would be totally forgotten today except that its name ended up on its replacement, the 1930, 53-story Lincoln Building.
If you look very closely, entrance kiosks for the original IRT subway are visible:
The IRT opened in 1904 and I believe that the kiosks were built towards the end of construction. 1904 would therefore seem to be the earliest possible date for this picture.
The tall building on the right is the Hotel Manhattan, at 42nd and Madison. It was built in two phases, 1896 and 1900 and was, supposedly, the birthplace of the cocktail “The Manhattan.”
The New York Public Library is conspicuous by its absence, but there’s a big construction fence where it should be. The exterior masonry walls were going up in 1906 and 1907, so we seem to have found the latest date. Also, by 1908, the work to replace Grand Central Station with the much larger Grand Central Terminal was in full swing.
Finally, the 42nd Street station of the Sixth Avenue el (the Swiss chalet at the lower left in picture below) and the south half of the 1904 New York Times Building, which was then gleaming white:
The high-rises along 42nd are new, the facade of Grand Central was new(and about to be demolished and replaced by something newer), the subway was new, the library was under construction… The street as we know it was created in a the space of maybe 15 years.