Celebrate the lighting of the world's most famous Christmas tree live with NBC personalities and a popular musical lineup singing holiday favorites. Celebrate the lighting of the world's most famous Christmas tree live with NBC personalities and a popular musical lineup singing holiday favorites. Celebrate the lighting of the world's most famous Christmas tree live with NBC personalities and a popular musical lineup singing holiday favorites. Celebrate the lighting of the world's most famous Christmas tree live with NBC personalities and a popular musical lineup singing holiday favorites.