The rostrum was a platformed area on Stratos where enemies of the Stratos city-dwellers were tied to an upright to face public questioning. In reality, the rostrum, which faced a series of emitters, served purely as a torture device that delivered "rays" to the entire body of whomever was tied to the upright. Ardanan high advisor Plasus was fond of utilizing the rostrum on Troglytes in an attempt to uncover information about the Disrupters, because he found that "physical discomfort is extremely persuasive."
In 2268, Plasus threatened to have a non-permitted Troglyte secured to the rostrum during his continued attempt to acquire the names of the Disrupters. The Troglyte, however, chose to face death instead of the rostrum, by jumping from the balcony to the planet's surface below.
After Vanna's unsuccessful attempt to take James T. Kirk hostage, she was taken to the rostrum in yet another of Plasus's attempts to reveal who the Disrupters were. When Kirk heard Vanna's screams, he came to intervene, and was appalled by his torture technique, threatening that "the only way you'll use that device again is on one of us." Plasus, who was amused by Kirk's "imposing display of primitive gallantry", eventually relented to Kirk's demands, and had "the prisoner" taken to confinement quarters. (TOS: "The Cloud Minders")