After a great vacation, I always try to think about what new things I learned. For example, Italian women in Rome can eat pasta three times a day and still look amazing.
More importantly, though, I learned the origins of our own profession -- marketing and public relations. The great walking tours we took using througheternity.com (which I highly recommend) taught us that beyond the road systems, aqueducts for irrigation, sewage systems and some of the most amazing artwork and architecture I've ever seen, the Romans were early proponents of branding and PR. The Roman Coliseum, the Circus Maximus and all of the various theaters were designed to promote the latest rulers -- their might, their conquests and their ability to keep their people happy with regular entertainment -- grisly entertainment, but at the time better than the World Wrestling Federation and Nascar rolled into one.
There was definitely more of a cult of personality type of branding of current rulers back then. But it certainly set the stage for promoting the leaders of the time and their accomplishments. And they certainly knew how to make that branding endure the test of time.

