See Taylor Swift, Ariana Grande, Pharrell and More Light Up NYC Jingle Ball

On Saturday night, a handful of the world's biggest pop stars (Taylor Swift, Ariana Grande, Gwen Stefani, Iggy Azalea, Maroon 5 and more) descended upon Madison Square Garden for the annual Z100 Jungle Ball, a rapid-fire concert showcasing the year's biggest Top 40 hits. "Birthday girl Taylor Swift was the undisputed......