When you think of the global contributions to Rockefeller Center, you might think of French Art Deco, which had an enormous influence on the modernist design of the complex, or go all the way back to Greek mythology, at the heart of the Plaza's most celebrated sculptures. Perhaps less obvious, though, is the profound impact of Italian arts and culture on the site, and of the nation's immigrants who brought their talents and skills to NYC in the early 20th century, helping to shape some of the Rock Center's enduring gems—including the Christmas Tree tradition itself.

Roman Bronze Works: Riccardo Bertelli, a native of Genoa, opened Roman Bronze Works in Greenpoint, Brooklyn, circa 1899. It was, as noted by the Metropolitan Museum of Art, "the first foundry to specialize exclusively" in the lost-wax casting method, and became the foremost destination for sculptors to have their work cast in bronze over the next century. Bertelli, whose guidance on executing the pieces was often sought out by artists, moved the shop to the former Tiffany studios in Queens in 1928, and over the following decade produced many major works of art for Rockefeller Center. In 1933, Paul Manship sculpted "Prometheus" for Rockefeller Plaza, creating a full-size plaster figure that was then cast at Bertelli's studio, according to Christine Roussel's The Art of Rockefeller Center. The uncoated bronze sculpture made its Plaza debut in January 1934, and as the finish was still under debate, didn't receive its first gilding until 1937.

Donald Deskey, the designer of Radio City Music Hall, had three nude sculptures for the venue cast at Roman Bronze (Gwen Lux's "Eve," Robert Laurent's "Girl and Goose," and William Zorach's "Spirit of the Dance"), and Rene Chambellan's effervescent Tritons, Nereids and sea creatures of legend, seen frolicking along the fountains of the Channel Gardens, were also cast there, as were his whimsical drain covers in the forms of a crab, starfish and turtle. Chambellan collaborated with Lee Lawrie on "Atlas," the plaster model of which had to be cut into 69 pieces before Roman Bronze could work its magic. After casting, Roussel writes, "The parts were then welded together to form 12 large sections. These sections were then assembled to form the complete sculpture," weighing in at seven tons.

In the 1940s, the Schiavo family, who had worked with Bertelli since the early days, purchased the foundry and kept it operating for decades. More about the company's legacy can be found in the book A Century of American Sculpture: The Roman Bronze Works Foundry by Lucy D. Rosenfeld.

"Italia" and "The Immigrant": It's no accident that Rockefeller Center feels like the crossroads of the world. Its founder, John D. Rockefeller Jr., successfully cultivated international relationships, beginning with buildings dedicated to Britain and France (the British Empire Building and La Maison Française, on either side of the Channel Gardens). The story of Palazzo d'Italia, at 50th Street and Fifth Avenue, is much more fraught, as its opening coincided with the Fascist rise of Benito Mussolini and consequently World War II, when the U.S. and Italy were at war. Read more about the complicated history of the building and its original artwork here.

Nearly 20 years after the war ended, in 1963, the Italian sculptor Giacomo Manzù, who had just completed monumental bronze doors for St. Peter's Basilica in the Vatican, submitted a design for a new plaque for the Palazzo's Fifth Avenue facade. It became the simple yet striking bas-relief "Italia," contrasting an austere background against an entwined bounty of grape leaves, vines and wheat. Read more about the modern sculpture here. A smaller plaque on the side entrance of the building is "The Immigrant," which depicts the struggle of Italian refugees after the war, showing a mother, traveling with her belongings tied into a sack on a pole, comforting her crying child. Amid the image's anguish, it also, as Roussel writes, offers a "straightforward message of hope to the millions of Italian immigrants who made their way to America."

The Christmas Tree: The very first Christmas Tree didn't come with a lot of fanfare—it appeared on the construction grounds of the future Rockefeller Center in 1931. As shown in our slideshow on the tree's history, "During the excavation of the Rockefeller Center site, demolition workers lined up beneath the tree to collect their paychecks during the height of the Great Depression. It was decorated with handmade garlands made from the tinfoil ends of blasting caps used in the excavation." The New York Times delved into the story in its 2015 article "The Hard-Working Italian Origins of the Rockefeller Center Christmas Tree," speaking with the descendants of Cesidio Perruzza, who first arrived in the U.S. from Italy in 1901 and can be seen in the 1931 Christmas photo. His grandson, Steve Elling, said, "My grandfather took up a collection amongst his men to purchase the tree," and brought it to the site. So this year, when you see the towering tree sparkling with multicolored lights, remember its humble start more than 85 years ago, the resourceful, big-hearted workers behind it, and the spirit of people who migrated to this country, pooled their possessions and began a treasured new American tradition.