If you loved the Emmy-award-winning PBS series Downton Abbey, get yourself to St. Augustine, Fla., before January 7, 2018. The historic coastal city is the last stop on a nine-city tour for the collection of elegant, vintage costumes billed as Dressing Downton: Changing Fashions for Changing Times. It runs now through the beginning of the new year and brings the Gilded Age – end of Civil War to Stock Market crash in 1929 – into sharp relief. Staged on the third floor Ballroom Gallery in the historic city’s Lightner Museum, 36 costumes drape mannequins staged in “rooms” decorated with vibrant Asian rugs, and turn-of-the-20th-century fine art and furniture from the museum’s collection. In a mockup of an early 1910s century room – one of…