Yes you can build huge muscles with calisthenics! Look no further than football legend Herschel Walker

Herschel Walker at the age of 56

Is it possible or not to build big muscles with bodyweight training only or weights are crucial? This debate will go on as long as humanity exists but I'll put my 5 cents regardless. 

Instead of long talking I'll just show. Meet Herchel Walker, an American football legend, Olympic bobsledder, track sprinter and a man who started pro mma career well into his 50's(look at the photo above). And he attributes all his training success and longevity to his own high rep bodyweight training system  that he follows religiously since he was a kid.   

High rep calisthenics which according to traditional bodybuilding dogma won't build any muscle just endurance turned him into 6 ft 1 in(1.85 m) 225 lbs(102 kg) powerhouse.

Up until present day Walker follows his daily bodyweight training regime doing on average 1500 push ups, pull ups and 2500 sit ups plus he does lots of sprints, different variations of bodyweight squats and jump squats, walking lunges, etc. He does sets until his muscles start feeling burning and listen to his body so he's doing enough to be recovered the next day. You can find out more about his Basic Training here

As I mentioned earlier, he believes that his bodyweight-only program protects the joints and promotes fitness longevity.