NBC kicks off the holiday season by lighting one of the world's most famous Christmas trees in the heart of New York City for the 90th time with the annual "Christmas in Rockefeller Center."Viewers are treated to festive performances by Jimmie Allen, Andrea Bocelli along with Matteo Bocelli and Virginia Bocelli, David Foster and Katharine McPhee, Brett Eldredge, Mickey Guyton, Alicia Keys, The Muppets of Sesame Street, Dan + Shay, Blake Shelton, The Shindellas, Gwen Stefani, Louis York and more. The evening also includes a performance by the Radio City Rockettes from their iconic "Christmas Spectacular" and a special bit by Amy Poehler and Maya Rudolph. Plus, Shelton and Stefani deliver a rare nationally televised duet of their holiday single, "You Make It Feel Like Christmas."NBC News "TODAY" co-anchors Savannah Guthrie, Hoda Kotb, and Craig Melvin, with "Access Hollywood" host Mario Lopez, co-host the highly anticipated live telecast.The holiday special celebrates the lighting of an 82-foot-tall, 50-foot-wide Norway spruce from Queensbury, New York. The tree weighs approximately 14 tons and will be adorned with more than 50,000 multi-colored LED lights and topped with a three-dimensional Swarovski star covered in 3 million crystals.