I haven't paid too much attention to 669 Fifth Avenue. Plans were filed for an Alt 1 vertical expansion back in 2005, though work didn't get going until 2013. The building's been shrouded in scaffolding and netting ever since, and has become one of those peripheral construction hulks that are all too common round here. Work seems to have limped along over the years, accompanied by failure to maintain and safety violations (scaffolding unsafe and/or without permits). The DoB information for 669 isn't very helpful with alteration details; the virtual job folder is empty.
A few days ago I noticed a new(ish) SWO on the building:
BORO COMM HAS ORDERED ALL WORK STOPPED UNDER PERMIT# 302252390 11/10/16.(CONTRACTOR WITHDRAWAL)
It seems a good partner for 657-665 Fifth, at the other end of the block, now entering its twenty-first month of inactivity.