The chairs that were originally on every executive floor of the building were designed by Charles Eames, and manufactured by Herman Miller. They have become known as the Time-Life Chairs. In 1959, Eames asked Time-Life chairman Henry Luce "for photographs from the Time-Life archive to be used in a slideshow he was creating for the U.S. pavilion at the Moscow World Exhibition. Luce agreed, as long as Eames promised to return the favor one day. The following year, Eames made good on that promise, and 50 years later, the world is still enjoying the results of that arrangement."
These are the chairs you'll see in the Mad Men conference rooms, for the most part (Don had a different chair in his office). They are still in production, though a fifth leg has been added.
Courtesy: gothamist.com