In the 54 years since the 911's introduction, few production cars have undergone such continuous development — and stayed as true to the original concept. The engine is still rear-mounted, and the exterior design can be traced back to the first 911 to roll off the production line. Now, Porsche has another milestone to add to an already overflowing trophy case. The One Millionth 911 drove off the assembly line in Zuffenhausen, an Irish Green Carrera S, complete with a commemorative plaque and a few unique features that hark back the first 911. Unlike virtually every other 911 in history, this one won't be sold, but will instead embark on a world tour before going on display at the Porsche Museum.