As Jason, 36, gears up for his new role as an ESPN analyst on Monday Night Football this upcoming season ... spent much of his team working on his man cave and home library.

Picture a room with low lighting, the soft buzz of a mini fridge, and the sound of a football match blaring from a huge TV.

Former Philadelphia Eagles center Jason Kelce appears to be thriving now that he's retired from professional football. According to a report from The U.S. Sun, Kelce built a $15,000 man cave after ...