Have only been once in 2004 and I was a client/guest of a vendor.
Arrived on the grounds Saturday am around 9 or 10 when the first groups were teeing off #1.
My host guided us to the back 9 first where we walked barefoot down some fairways as there were no players and almost zero patrons in sight.
It was an geat way to see the famous holes without the crowds and was one of my favorite moments of the day.
Why barefoot?
It was kinda surreal actually.
Had flip flops on anyway on a gorgeaous spring day.
Walked down 10th hole and, upon seeing no one around of note, we kicked off the flippies and just enjoyed the grass on our feet.
Not sure if that can be done today, but it was a memorable experince for sure.