This scaffolding is enveloping an apparent vintage "taxpayer"holdout see In Context shot. ... A "taxpayer" is a two to three story building which acts as a placeholder until the owner can get the funds to build something taller or the price he wants to sell out to another developer. Why this holdout has survived so long may be hinted at by the King for Corners sign at top right (see Notes).
Scaffolders and King for Cornerssign, Midtown Sixth Avenue