Seen it. I only slowed down to look, I wasn't all that impressed.
Kind of like the "Great Meteor Crater" further down 66. Yeah, 15 bucks to stare at a huge hole in the ground. No thanks.
However, I am pretty much convinced that's where the moon landing was staged.
I lived in Flagstaff for 3 years.
Route 66 was actually my old street address.
Anyway, I went to that damn crater about 10 times to stare at it when friends and family came to visit. Once was enough.