"It makes me think about the whole team that it takes to put a musical number together. From recording it to being in the studio to dance rehearsals to putting it on film. To think we've done that 500 times is kind of mind-blowing," he says.
But what are Glee's 10 Best Musical Performances out of those 500? Check out ETonline's ranking and then weigh in with your own choices!
Don't Stop Believing, performed by the original New Directions. Watch!
Teenage Dream: Parts 1 and 2, performed by Darren Criss. Watch! Watch!