That’s a photo of the George Blumenthal house at a much earlier stage of construction than yesterday’s view. The foundations look to be complete and the first floor is framed out, although it’s buried under so much temporary wood plank that I can’t tell if the floor itself has been built yet. Something like thirteen columns have been erected above the first floor – some to the second floor elevation and some to the third – by the big crane in the middle and its little helper cranes. Note that the left side of the photo, past the wood fence, is an unrelated site also in construction but with no steel visible.
The heavy-timber sidewalk bridge is in construction along Park Avenue, in the foreground. Most likely, after the east side along Park was finished, they turned the corner and built the 70th Street bridge along the north side of the site. There are both A-frame and straight ladders – all wood – being used to build the bridge. The 70th Street side of the site is largely occupied by piles that look like brick, sand, and either coarse aggregate or cement.
The context of the site is telling a different story. On the far left, on the south side of 69th Street, is a row of ordinary brownstone rowhouses. Facing them, on the north side of 69th Street, are a series of fancier houses, with the light-colored one past the other vacant lot on the left side of that row. There’s one ornate house on the south side of 70th Street, immediately past the Blumenthal site, and then more rowhouses, better seen in yesterday’s photo. It’s not a coincidence that the two sites at the end of the block, facing Park Avenue were being built simultaneously. In 1912, these were the most desirable lots. A few years earlier they were not: the old Grand Central Station had been served by steam locomotives, and the approach tracks ran in an open cut at the center of Fourth (Park) Avenue. Electrification was completed in 1907 during the piecemeal demolition of the station and its replacement by the new Grand Central Terminal. The tracks along the avenue were roofed over, and one of the most polluted streets in New York became one of the nicest, clean and wider than average. So in the years following the electrification, Park Avenue experienced a localized building boom that specifically included rather extreme gentrification, from industrial and low-end residential to mansions like this one.