Secret to Warren Buffett's success; CNN's Poppy Harlow tours his Omaha office for a clue: 'no email'

What is the secret to Warren Buffett's success? Perhaps the clue lies in his office.

The oracle of Omaha is arguably one of the best investors of all time, and one of the richest men in the world. But you wouldn't necessarily know that by the looks of Buffett's office. Though it's not everyday one gets a tour of it, that's exactly what he gave CNN’s Poppy Harlow.

The chairman of Berkshire Hathaway showed her around his Omaha headquarters. From sports jerseys to a model Mars Rover, to a presidential medal of freedom and a very old tube TV, what she found—and didn't find—might surprise you.