Obviously 11th September 1941 was the Ground Breaking Ceremony of the Pentagon, and exactly sixty years later it was attacked, interesting isn't it?
Please look to right of link:-
The Pentagon - Wikipedia, the free encyclopedia
I'll come back to this with star alignments later, as the attack was aligned to an Osiris star and hermetic religion that looks like the day was chosen because of this.
I'm getting ready to show Calendar reform in Rome in 1582 tomorrow, don't rush me, ha ha!