I know about the 1972 date, but I've never heard of this "underground city" - do you have any information you can post about it?
I’ve not been able to find much of anything about it online. However, I live about a half hour drive from Georgetown, and I’ve been hearing all the locals talk about it for years, including a number, who claim to have been part of the construction/excavation crew in the late sixties-early seventies.
I’ve also seen the property from ground level on numerous occasions. Sixty five acres of immaculately mowed lawns and pancake-flat grounds smack in the middle of hilly country, and with hills on every side of the property. The only ground level buildings to be seen are what looks like a barn, and a secondary building not much bigger than a farmhouse. Not exactly all that impressive for buildings that supposedly house the Canadian headquarters of Watchtower.
By comparison, The Seventh Day Adventists have their Canadian headquarters in Oshawa Ontario, and they easily have four times the above-ground building and office space that Watchtower does.
Make of all of that what you will.
When I was a child and asked how Jehovah was going to kill every person in the world that wasn’t a JW without killing a JW standing right next to him, I was told to have faith in Him because he can do anything.
These people, if they did build an underground shelter, s/h/b/ admonished for lack of faith. And they better have plenty of supplies, because it’s been 100 years since their first date for Armageddon was 1914. (which was changed after further enlightenment)