Bernardo Bellotto was a court painter to August III—Poland’s 18th-century king and the Elector of Saxony. Bellotto was also the nephew of Giovanni Antonio Canal—the great painter Canaletto. For many years Bellotto was overlooked, hidden in his uncle’s long shadow. But his landscape paintings, panoramic yet detailed, have grown in stature and won admiration. Among the most beautiful are his five paintings of Königstein, an enchanted fortress 25 miles southeast of Dresden. The two-meter works are part of Bellotto’s 30-painting series of Dresden views, all of which are here together for the first time in more than 250 years. —E.C.