Even on a tight schedule, Odeon of Herodes Atticus (daytime view) earns the hours.
Allow 10–20 min.
Even without a show, the towering arched façade and the sweep of stone seating are one of the most photogenic stops on the Acropolis south slope, included on the main ticket. The catch: outside festival nights you only view it from above the railings — you can't go down onto the seats or stage.