ABC News "Good Morning America" anchors Robin Roberts and Josh Elliott will broadcast live from St. Peter's Square in Vatican City on Wednesday, December 18. They will join the thousands in the Square attending Pope Francis" weekly General Audience as million of Catholics worldwide prepare for Christmas. Additionally, Roberts has a behind-the-scenes tour inside the Vatican, including the Terza Loggia of the Sacred Apostolic Palace - the Vatican's "West Wing" - and show viewers spectacular and rarely-televised views of Rome and St. Peter's Basilica. Plus, Elliott will have a behind-the-scenes report on the legendary Pontifical Swiss Guard, the men who protect the Pope, and their long-standing traditions, and GMA viewers will see a special performance by The Sistine Chapel Choir. Follow along all morning with Robin and Josh on Twitter and Instagram with hashtag #GMAatTheVatican. We'll be asking what viewers are grateful for this Christmas with the hashtag #GratefulThisChristmas and will be reading some of the tweets on air from St. Peter's Square. Promo Link: http://abcnews.go.com/GMA/video/christmas-vatican-21253062 "Good Morning America" is a two-hour, live program anchored by Robin Roberts and George Stephanopoulos. Josh Elliott is the news anchor, Lara Spencer is lifestyle anchor and Ginger Zee is the weather editor. Tom Cibrowski is the senior executive producer. The morning news program airs MONDAY-FRIDAY (7:00-9:00 a.m., ET), on the ABC Television Network.