Going back a few centuries, the Macedonian ploughboy (some say swineherd) Justin who spent the last nine of his 77 years as emperor of Byzantium proved a popular subject for opera. As romanticized by the librettist Nicolò Beregan, his story was set to music by composers including Albinoni in 1711 and Handel in 1737, with Vivaldi staking his claim exactly halfway in between, in 1724. The court theater at the Swedish palace of Drottningholm, a lazily delightful boat ride through the greensward from Stockholm, dates to 1766 and retains its Baroque stage machinery in full working order. Seating, be warned, is tight—no picnic on a hot day, and the endless summer days can be very hot. (The Swedish capital has been known to tie temperature records with Athens.) In the title role, the sublime Ukrainian countertenor Yuriy Mynenko dispatches a half dozen arias or so, demonstrating fluency and expressive nuance in prismatic registers. Baroque opera being Baroque opera, a handful of other principals are just as lavishly provided for. —Matthew Gurewitsch