In a letter of 1555, Bartolomeo Ammannati, one of the four architects of the Villa Giulia in Rome, described the main building, or casino, as resembling an ancient theater. Scholars of the building have rarely followed this clue to investigate the intended uses of the villa, which was built between 1551 and 1555 for Pope Julius III, who died in March of the latter year. According to Ammannati, the villa was almost finished at the pope’s death. Julius, however, did not live long enough to sponsor any performances in a completed complex. The essay proposes that Julius intended the courtyard of the villa as the site of theatrical entertainments. Julius’s interest in public spectacles, including jousting, pageants and comedies, is well documented. Three drawings related to different moments in the design history of Villa Giulia are analyzed in terms of the theatrical forms they employ. Both the relation of the villa’s design to contemporary theatrical performances and to the widespread contemporary interest in jousting and tourneys lend credence to the thesis. The article notes the influence of the villa on subsequent work by Ammannati; on a design of a second architect of the villa, Giacomo Barozzi da Vignola; and on Pirro Ligorio.