Because it’s so famous, everyone and their mother are trying to go see it. Be prepared for massive traffic jams in and out of the site, and be prepared to pay ridiculous prices to park your car. It’s in the middle of nowhere so it’s not like you can just take the freeway to the site and use a convenient 5 story parking garage.
Also, be wary of the mystics and conspiracy theorists haunting the place. They’re always out there looking to perform rituals and convert the masses.