On March 15, 1978, a crowd gathered in Rome’s Gallerie dell’Oca for a show titled “Mario Merz, Balla, Carrà, de Chirico, de Pisis, Morandi, Savinio, Severini.” The idea was to put work by Merz, a member of the Arte Povera avant-garde, side by side with works by other 20th-century luminaries. The city was abuzz. The show was a critical success. For the second edition of its series “Mostre in Mostra” (Exhibitions on Display), Palazzo delle Esposizioni recreates that landmark show. —Elena Clavarino