The scene is Acragas, a city in Sicily. The time is about a hundred years before Nico and Diotima, so we're talking 6th century BC. Back then Sicily was Greek and Acragas was ruled by a tyrant named Phalaris, who was renowned for his cruelty.
In fact, the reputation of Phalaris was so well-known that an Athenian by the name of Perillos came to the tyrant with a suggestion. Why not, he said, build a bull out of hollowed bronze? The tyrant's enemies could be shut inside and then a fire set underneath the brazen beast's body so that the tyrant's enemies roasted to death.
Phalaris thought roasted enemy was a terrific idea. He commanded Perillos to build the brazen bull. The statue had a door in the side for easy access. Pipes were installed inside that ran to a horn in the bull's mouth, so that the victim's screams would emerge as a bull's roar.
Quite why Perillos came to the tyrant with the idea in the first place is unknown, but presumably he was either in it for the money or else was a fellow-traveling sadist. Either way, legend has it that when the bull was ready for its first run, that Phalaris the Tyrant ordered Perillos be the first victim. This is so neatly according to the usual narrative that it's probably an invention.
The brazen bull, however appears to have been a for-real instrument of torture. No less than Pindar mentions it in a praise song, a hundred years after the event. (This is the same Pindar who appears in Sacred Games, which is what brought the whole story to my attention.) Pindar had this to say:
The kindly excellence of Croesus does not perish, but Phalaris, with his pitiless mind, who burned his victims in a bronze bull, is surrounded on all sides by a hateful reputation.Pindar takes it for granted that everyone knows the story of the brazen bull. Phalaris clearly had a public relations problem.
Cicero and Diodorus get into the act a few hundred years later. Between them they say that the brazen bull was eventually captured by the Carthaginians who took if back to Carthage. Since the Carthaginians most certainly did practice human sacrifice, there's a fair chance the brazen bull saw continued use. It was later returned to its home by Scipio after he conquered Carthage, after which the brazen bull somewhat thankfully disappears from history.