The popularity of the Boeing 737 is no secret, with almost 12,000 aircraft across all variants of this narrowbody twinjet family having been produced since the mid-1960s. The 737 family as a whole is split into the Original, Classic, Next Generation, and MAX series, with the largest variant of the Classic sub-family being the 737-400. Almost 500 examples of these planes were produced, but which are the oldest today?