Back in 2014, FX’s sister network FXX put itself on the map by presenting a marathon of all 552 episodes then produced of Fox’s The Simpsons – a 12-day marathon that set records as the longest TV marathon in history. Well, history marches on, as does The Simpsons. Today at noon ET, FXX presents a new compilation of Simpsons episodes, a mega-marathon that now covers 600 episodes, presented over 300 hours, represents 27 seasons, and will take 13 days to complete, finishing up at midnight on Dec. 7. Be forewarned: the last marathon was addictive, and once you tune in, it’s hard not to settle in. I expect no less from this marathon. Alan Sepinwall and Matt Zoller Seitz, in their new book TV: The Book, rank The Smpsons among the best television series ever made – and it’s easy to agree with them. The slow but delightful Simpsons march down memory lane begins at noon.