Gorgeous people drinking at work in the sixties and getting away with behaviour that'd get you sacked in minutes today.
Fun fact: Matthew Weiner wrote the pilot in 1999; every major network rejected it before AMC greenlit it in 2006.
Posh people having extremely polite arguments over dinner while the staff do all the actual work downstairs.
Fun fact: Highclere Castle, the real filming location, was once home to the discoverer of Tutankhamun's tomb.