I'm posting this info so anons who are expert at knowing where to locate records on secret tunnels will see this. Normie here and I have no clue where to find this info. Will give as much info as I can without doxing myself.
Please investigate for the existence of secret tunnels (other than the NYC subway tunnels) under 666 Fifth Ave.
I used to work in music. At one point I worked for a band that headlined Radio City Music Hall (1260 Sixth Ave.) which is 1 block from ROCKEFELLER Center and 3 blocks from 666 Fifth Avenue.
There are tunnels under Radio City, not just the one sited in some articles that leads to Rockefeller Center. When my ex-employer played Radio City, they escorted the band to/from their hotel to the theater through a non-public tunnel. The hotel was NOT in Rockefeller Center.
In a very "Spinal Tap" way, I tried to find my way (with no guide this time) back to the hotel with a member of the opening band and we got very lost but eventually found our way. This happened decades ago … well before Spinal Tap ("Hello, Cleveland!)
I looked on a map for all hotels near Radio City to see what direction we were going in, but there's nothing nearby so that hotel may no longer exist. I don't remember the name. (It was decades ago and I'm old. Sorry.)
Look for connections to the Rockefellers to that building (Rockefeller Center is 2 blocks away) and look for tunnels.
Here's an article about "Secrets of Radio City" mentioning a tunnel that goes from RC to Rockefeller Center.
See Point #4:
https:// www.amny.com/secrets-of-new-york/secrets-of-radio-city-music-hall-1.8047124
We ended up in what seemed like an endless underground maze, so must be more than just this one.