Aside from doors, Elvis had security camera monitors based in the kitchen, his father Vernon’s office and upstairs in his bedroom.

You can see the ones on the food counter during the Graceland tour, which are still in use to this day.

During a virtual tour of the mansion that Express.co.uk took part in, archivist Angie Marchese said: “This was a security system Elvis had added in the sixties, so he could kind of see what was going on here at Graceland whenever he was here. He really had an open-door policy that if you were a friend of his and you wanted to bring somebody out to Graceland, Graceland was your house too. So you could bring anyone out you wanted to. The only place that no one was allowed to go was upstairs, without being personally invited by Elvis himself.”