Our guest has had a front row seat for a good chunk of rock and roll’s history. And thankfully for us, he has had a camera with him the entire time. Bob Gruen is best known for his iconic image of John Lennon in the New York City t-shirt. Arms folded in front of him, looking through dark sunglasses, part of the New York Skyline behind him. Gruen calls that photo his “hit single,” and it’s one of many photos from 40 years of rock n roll featured in his new book, “Rock Seen,” published in 2011 by Abrams New York.